TECHNICAL  INSTRUCTION  SERIES 


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PAUL 


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HANDICRAFT  SERIES. 

A  Series  of  Practical  Manuals. 

Edited  by  PAUL  N.  HASLUCK,  Editor  of  "Work,"  "Technical  Instruction 

Q~-:~-  »  *tc. 


House  Decorati*-  x 

With  79  Enr       ,  \ 
Contents. — Co1  V> 
Painters.    Ho-  Q< 


^        tging,  Painting,  etc. 

^ Sj      "*tc.    Tools  used  by 
\y  x  Whitewashing 


AS 


HANDICRAFT  SERIES  {Continued). 


Building  31odel  Boats.    With  168  Engravings  and  Diagrams. 

Contents. — Building  Model  Yachts.  Rigging  and  Sailing  Model  Yachts.  Making  and 
Fitting  Simple  Model  Boats.  Building  a  Model  Atlantic  Liner.  Vertical  Engine  for  a 
Model  Launch.  Model  Launch  Engine  with  Reversing  Gear.  Making  a  Show  Case  for 
a  Model  Boat. 

Electric  Bells,  How  to  Make  and  Fit  Them.    With  162  Engravings  and  Diagrams. 

Contents. — The  Electric  Current  and  the  Laws  that  Govern  it.  Current  Conductors 
used  in  Electric-Bell  Work.  Wiring  for  Electric  Bells.  Elaborated  Systems  of  Wiring; 
Burglar  Alarms.  Batteries  for  Electric  Bells.  The  Construction  of  Electric  Bells,  Pushes, 
and  Switches.    Indicators  for  Electric-Bell  Systems. 

Bamboo  Work.    With  177  Engravings  and  Diagrams. 

Contents. — Bamboo:  Its  Sources  and  Uses.  How  to  Work  Bamboo.  Bamboo  Tables. 
Bamboo  Chairs  and  Seats.  Bamboo  Bedroom  Furniture.  Bamboo  Hall  Racks  and  Stands. 
Bamboo  Music  Racks.  Bamboo  Cabinets  and  Bookcases.  Bamboo  Window  Blinds. 
Miscellaneous  Articles  of  Bamboo.    Bamboo  Mail  Cart. 

Taxidermy.    With  108  Engravings  and  Diagrams. 

Contents. — Skinning  Birds.  Stuffing  and  Mounting  Birds.  Skinning  and  Stuffing 
Mammals.  Mounting  Animals'  Horned  Heads:  Polishing  and  Mounting  Horns.  Skin- 
ning, Stuffing,  and  Casting  Fish.  Preserving,  Cleaning,  and  Dyeing  Skins.  Preserving 
Insects,  and  Birds'  Eggs.    Cases  for  Mounting  Specimens. 

Tailoring.    With  180  Engravings  and  Diagrams. 

Contents. — Tailors'  Requisites  and  Methods  of  Stitching.  Simple  Repairs  and  Press- 
ing. Relining,  Repocketing,  and  Recollaring.  How  to  Cut  and  Make  Trousers.  How 
to  Cut  and  Make  Vests.  Cutting  and  Making  Lounge  and  Reefer  Jackets.  Cutting  and 
Making  Morning  and  Frock  Coats. 

Photographic  Cameras  and  Accessories.     Comprising  How  to  Make  Cameras, 
Dark  Slides,  Shutters,  and  Stands.    With  160  Illustrations. 
Contents. — Photographic  Lenses  and  How  to  Test  them.  Modern  Half-plate  Cameras. 
Hand  and  Pocket  Cameras.    Ferrotype  Cameras.    Stereoscopic  Cameras.  Enlarging 
Cameras.    Dark  Slides.    Cinematograph  Management. 

Optical  Lanterns.  Comprising  The  Construction  and  Management  of  Optical 
Lanterns  and  the  Making  of  Slides.  With  160  Illustrations. 
Contents. — Single  Lanterns.  Dissolving  View  Lanterns.  Illuminant  for  Optical  Lan- 
terns. Optical  Lantern  Accessories.  Conducting  a  Lime-light  Lantern  Exhibition.  Ex- 
periments with  Optical  Lanterns.  Painting  Lantern  Slides.  Photographic  Lantern 
Slides.    Mechanical  Lantern  Slides.    Cinematograph  Management. 

.Engraving  Metals.    With  Numerous  Illustrations. 

Contents. — Introduction  and  Terms  used.  Engravers'  Tools  and  their  Uses.  Ele- 
mentary Exercises  in  Engraving.  Engraving  Plate  and  Precious  Metals.  Engraving 
Monograms.  Transfer  Process  of  Engraving  Metals.  Engraving  Name  Plates.  En- 
graving Coffin  Plates.  Engraving  Steel  Plates.  Chasing  and  Embossing  Metals.  Etch- 
ing Metals. 

Basket  Work.    With  189  Illustrations. 

Contents. — Tools  and  Materials.  Simple  Baskets.  Grocer's  Square  Baskets.  Round 
Baskets,  Oval  Baskets.  Flat  Fruit  Baskets.  Wicker  Elbow  Chairs.  Basket  Bottle- 
cas;  doctors'  and  Chemists'  Baskets.    Fancy  Basket  Work.    Sussex  Trug  Basket. 

Miscellaneous  Basket  Work.  Index. 

Bookbinding.    With  125  Engravings  and  Diagrams. 

Contents. — Bookbinders'  Appliances.  Folding  Printed  Book  Sheets.  Beating  and 
Sewing.  Rounding,  Backing,  and  Cover  Cutting.  Cutting  Book  Edges.  Covering 
Books.  Cloth-bound  Books,  Pamphlets,  etc.  Account  Books,  Ledgers,  etc.  Coloring, 
Sprinkling,  and  Marbling  Book  Edges.  Marbling  Book  Papers.  Gilding  Book  Edges. 
Sprinkling  and  Tree  Marbling  Book  Covers.  Lettering,  Gilding,  and  Finishing  Book 
Covers.  Index. 

Bent  Iron  Work.    Including  Elementary  Art  Metal  Work.    With  269  Engravings 
and  Diagrams. 

Contents. — Tools  and  Materials.  Bending  and  Working  Strip  Iron.  Simple  Exercises 
in  Bent  Iron.  Floral  Ornaments  for  Bent  Iron  Work.  Candlesticks.  Hall  Lanterns. 
Screens,  Grilles,  etc.  Table  Lamps.  Suspended  Lamps  and  Flower  Bowls.  Photo- 
graph Frames.    Newspaper  Rack.    Floor  Lamps.    Miscellaneous  Examples.  Index. 

Photography.    With  Numerous  Engravings  and  Diagrams. 

Contents. — The  Camera  and  its  Accessories.  The  Studio  and  the  Dark  Room.  Plates. 
Exposure.  Developing  and  Fixing  Negatives.  Intensification  and  Reduction  of  Nega- 
tives. Portraiture  and  Picture  Composition.  Flash-light  Photography.  Retouching 
Negatives.  Processes  of  Printing  from  Negatives.  Mounting  and  Finishing  Prints. 
Copying  and  Enlarging.    Stereoscopic  Photography.    Ferrotype  Photography.  t 

DAVID  McKAY,  Publisher,  Washington  Square,  Philadelphia. 


HANDICRAFT  SERIES  {Continued), 


Upholstery.    With  162  Engravings  and  Diagrams. 

Contents. — Upholsterers'  Materials.  Upholsterers'  Tools  and  Appliances.  Webbing, 
Springing,  Stuffing,  and  Tufting.  Making  Seat  Cushions  and  Squabs.  Upholstering  an 
Easy  Chair.  Upholstering  Couches  and  Sofas.  Upholstering  Footstools,  Fenderettes, 
etc.  Miscellaneous  Upholstery.  Mattress  Making  and  Repairing.  Fancy  Upholstery. 
Renovating  and  Repairing  Upholstered  Furniture.  Planning  and  Laying  Carpets  and 
Linoleum.  Index. 

Leather  Working.    With  162  Engravings  and  Diagrams. 

Contents. — Qualities  and  Varieties  of  Leather.  Strap  Cutting  and  Making.  Letter 
Cases  and  Writing  Pads.  Hair  Brush  and  Collar  Cases.  Hat  Cases.  Banjo  and  Man- 
doline Cases.  Bags.  Portmanteaux  and  Travelling  Trunks.  Knapsacks  and  Satchels. 
Leather  Ornamentation.  Footballs.  Dyeing  Leather.  Miscellaneous  Examples  of 
Leather  Work.  Index. 

Harness  Making.    With  197  Engravings  and  Diagrams. 

Contents. — Harness  Makers'  Tools.  Harness  Makers'  Materials.  Simple  Exercises  in 
Stitching.  Looping.  Cart  Harness.  Cart  Collars.  Cart  Saddles.  Fore  Gear  and  Leader 
Harness.  Plough  Harness.  Bits,  Spurs,  Stirrups,  and  Harness  Furniture.  Van  and  Cab 
Harness.  Index. 

Saddlery.    With  99  Engravings  and  Diagrams. 

Contents. — Gentleman's  Riding  Saddle.  Panel  for  Gentleman's  Saddle.  Ladies'  Side 
Saddles.  Children's  Saddles  or  Pilches.  Saddle  Cruppers,  Breastplates,  and  other 
Accessories.  Riding  Bridles.  Breaking-down  Tackel.  Head  Collars.  Horse  Clothing. 
Knee-caps  and  Miscellaneous  Articles.  Repairing  Harness  and  Saddlery.  Re-lining 
Collars  and  Saddles.    Riding  and  Driving  Whips.    Superior  Set  of  Gig  Harness.  Index. 

Knotting  and  Splicing,  Ropes  and  Cordage.   With  208  Engravings  and  Diagrams. 

Contents. — Introduction.  Rope  Formation.  Simple  and  Useful  Knots.  Eye  Knots, 
Hitches  and  Bends.  Ring  Knots  and  Rope  Shortenings.  Ties  and  Lashings.  Fancy 
Knots.  Rope  Splicing.  Working  Cordage.  Hammock  Making.  Lashings  and  Ties  for 
Scaffolding.    Splicing  and  Socketing  Wire  Ropes.  Index. 

Beehives  and  Beekeepers'  Appliances.    With  155  Engravings  and  Diagrams. 

Contents. — Introduction.  A  Bar-Frame  Beehive.  Temporary  Beehive.  Tiering  Bar- 
Frame  Beehive.  The  "  W.  B.  C."  Beehive.  Furnishing  and  Stocking  a  Beehive.  Obser- 
vatory Beehive  for  Permanent  Use.  Observatory  Beehive  for  Temporary  Use.  Inspection 
Case  for  Beehives.  Hive  for  Rearing  Queen  Bees.  Super-Clearers.  Bee  Smoker. 
Honey  Extractors.    Wax  Extractors.    Beekeepers'  Miscellaneous  Appliances.  Index. 

Electro-Plating.    With  Numerous  Engravings  and  Diagrams. 

Contents—  Introduction.  Tanks,  Vats,  and  other  Apparatus.  Batteries,  Dynamos, 
and  Electrical  Accessories.  Appliances  for  Preparing  and  Finishing  Work.  Silver- 
Plating.  Copper-Plating.  Gold-Plating.  Nickel-Plating  and  Cycle-Plating.  Finishing 
Electro-Plated  Goods.    Electro-Plating  with  Various  Metals  and  Alloys.  Index. 

Clay  Modelling  and  Plaster  Casting.    With  153  Illustrations. 

Contents. — Drawing  for  Modellers.  Tools  and  Materials  for  Clay  Modelling.  Clay  Model- 
ling. Modelling  Ornament.  Modelling  the  Human  Figure.  Waste-Moulding  Process  of 
Plaster  Casting.  Piece-Moulding  and  Gelatine-Moulding.  Taking  Plaster  Casts  from 
Nature.  Clay  Squeezing  or  Clay  Moulding.  Finishing  Plaster  Casts.  Picture  Frames 
in  Plaster.  Index. 

Other  Volumes  in  Preparation. 

DAVID  McKAY,  Publisher,  Washington  Square,  Philadelphia, 


TEXTILE  FABRICS  AND  THEIR 
PREPARATION  FOR  DYEING 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/textilefabricsthOOhumm_0 


TEXTILE    FABRICS  AND 
THEIR  PREPARATION 
FOR  DYEING 


WITH  NUMEROUS  ENGRAVINGS  AND  DIAGRAMS 

BY 

PROFESSOR  J.  J.  HUMMEL,  F.O.S. 

LATE  DIRECTOR  OF  THE  DYEING  DEPARTMENT  OF  THE  YORKSHIRE  COLLEGE 
AND  LEEDS  UNIVERSITY 

NEW  AND  REVISED  EDITION 

EDITED  BY 

PAUL   ST.  HASLUCK 

HONOURS  MEDALLIST  IN  TECHNOLOGY 
EDITOR  OF  "WORK"  AND  "BUILDING  WORLD,"  ETC.  ETC. 

•  •••  '3       -       >  '  '    1  o  en  j  -1) 

r'  <*    ,  ri  „  ■  -1       "    '  )J, 

PHILADELPHIA  > 

DAVID    M  c  K  A  Y,  Publisher 

610,  SOUTH  WASHINGTON  SQUARE 
1906 


nob 


PREFACE. 


Textile  Fabrics  and  Their  Preparation  for  Dyeing 
contain?,  in  a  form  convenient  for  everyday  use,  a  comprehen- 
sive treatise  on  the  subject.  The  contents  of  this  manual  are 
based  on  the  highly  esteemed  book  written  by  the  late  Dr. 
J.  J.  Hummel,  F.C.S.,  Professor  and  Director  of  the"  Dyeing 
Department  of  the  Yorkshire  College,  Leeds. 

Without  omitting  any  essential  part  of  the  original  work 
the  matter  has  been  revised  and  brought  up  to  date  by  Mr. 
A.  R.  Foster,  Consulting  Textile  Expert,  City  and  Guilds 
Honours  Medallist.  Needless  to  say  many  changes  have  taken 
place  since  the  previous  edition  was  published,  and  whilst  the 
new  processes  and  appliances  have  been  incorporated,  the  older 
methods  which  are  still  in  vogue  in  less  progressive  works, 
have  been  retained  and  revised.  In  this  manner  the  manual 
has  been  made  valuable,  not  only  to  the  student  but  all 
employed  in  bleaching,  finishing,  and  dyeing  works. 

Readers  who  may  desire  additional  information  respecting 
special  details  of  the  matters  dealt  with  in  this  book,  or  in- 
structions on  any  kindred  subjects,  should  address  a  question 
to  the  Editor  of  Work,  La  Belle  Sauvage,  E.C.,  so  that  it  may 
be  answered  in  the  columns  of  that  journal. 

P.  N.  HASLUCK. 

La  Belle  Sauvage,  London, 
November,  1906. 


16010 


CONTENTS. 

CHAPTER  PAGE 

I.— Cotton   9 

II.— Flax,  Jute,  and  China  Grass   20 

III.  — Wool   29 

IV.  -Silk                                        '  .      .      .      .  47 

V.— Cotton  Bleaching   71 

VI. — Linen  Bleaching   88 

VII. — Mercerising   93 

VIII. — Wool  Scouring  and  Bleaching   96 

IX. — Scouring  and  Bleaching  Silk   119 

X.— Water  .    124 

XI.— About  Dyeing   145 

Index   15 


LIST    OF  ILLUSTRATIONS. 

FIG.  PAGE 

1.  — Cotton  Plant  9 

2.  — Appearance  of  Cotton  under  the  Microscope    ...  10 

3.  — Transverse  Sections  of  Cotton  Fibre       .       .       .  .11 

4.  — Transverse  Sections  of  Unripe  Cotton  Fibre    .       .  .11 

5.  — Transverse  Sections  of  Cotton  Fibre  after  Treatment  with 

Caustic  Soda   17 

6.  — Flax  Fibre  under  the  Microscope   24 

7.  — Microscopical  Appearance  of  Wool  Fibre  .  30 

8.  — Cells  of  Wool  Fibre  under  the  Microscope       ...  32 

9.  — Cross  Section  of  Typical  W^ool  Fibres     .       .  33 

10.  — Silk  Glands  of  the  Silkworm  48 

11.  — Section  of  Silk-bag  49 

12.  — Microscopic  Appearance  of  Haw  Silk  Fibre     ...  49 

13.  — Silk  Cocoon  50 

14.  — Microscopic  Appearance  of  Tussur  Silk  Fibre  .       .  .54 

15.  — Stringing  Machine  for  Silk       .       .       .  -     .       .       .  5G 

16.  — Details  of  Silk-stringing  Machine  57 

17.  — Silk-lustring  Machine  .       .       .       .       .       .  .59 

18.  — Conditioning  Apparatus  60 

19.  — Section  of  Conditioning  Chamber      .       .       .    •   .  .63 

20.  — Apparatus  for  Chemickiug,  Souring,  and  Washing  .       .  72 

21.  — Plate  Singeing  Machine,  by  Mather  and  Piatt       .       .  75 

22.  — Gas  Singeing  Machine,  by  Mather  and  Piatt  .       .       .  77 

23.  — Longitudinal  Section  of  the  Mather  Patent  Kier    .       .  79 

24.  — Section  of  Injector  Kier  82 

25.  — Five-bar  Expander,  by  My  cock  85 

26.  — Wool-steeping  Tank — Elevation  101 

27.  — Wool-steeping  Tank— Plan  101 


8 


TEXTILE  FABRICS. 


FIG.  PAGE 

28.  — Section  of  Furnace  for  Making  Yolk-ash        .       .  .102 

29.  — McNaught's  Wool-scouring  Machine — Elevation     .       .  104 

30.  — McNaught's  Wool-scouring  Machinev— Cross  Section       .  105 

31.  — Yarn-stretching  Machine     .   107 

32.  — Woollen  Yarn-scouring  Machine   109 

33.  — Continuous  Woollen  Yarn-scouring  Machine    .      .       .  110 

34.  — Woollen  Cloth-scouring  Machine   110 

35.  — Section  of  Machine  shown  in  Fig.  34       ...  Ill 

36.  — Woollen  Cloth  Open-width  Scouring  Machine  .       .       .  112 

37.  — Treble  Crabbing  Machine   114 

38.  — Sulphur  Stove  for  Woollen  Cloth  Bleaching     .       .  .116 

39.  — Porter-Clark's  Apparatus  for  Softening  Water — Plan     .  134 

40.  — Porter-Clark's  Apparatus  for  Softening  Water — Elevation  135 

41.  — Gaillet  and  Huet's  Apparatus  for  Softening  Water  .       .  138 

42.  — Gaillet  and  Huet's  Precipitating  Tank   139 

43.  — Purification  Works  for  Waste  Dye-liquors       .       .       .  142 


TEXTILE  FABRICS  AND  THEIR 
PREPARATION  FOR  DYEING. 


CHAPTER  I. 

COTTON. 

The  Cotton  Plant.— Cotton  is  the  white,  downy,  fibrous 
substance  which  envelopes  the  seeds  of  various  species  of 
the  cotton-plant,   Gossypium,  belonging  to  the  natural 


Fig.  1.— Cotton  Plant. 


order  Malvaceae.  The  seeds,  to  which  the  cotton  fibres  are 
attached,  are  enclosed  in  a  3-  to  5-valved  capsule,  which 
bursts  when  ripe;  the  cotton  is  then  collected  and  spread 
out  to  dry.  The  seeds  are  afterwards  separated  by  the 
mechanical  operation  termed  "ginning,"  and  the  raw 
cotton  thus  obtained  is  sent  to  the  spinner.    The  cotton- 


10 


TEXTILE  FABRICS. 


plant  (Fig.  1)  is  cultivated  with  success  only  in  warm 
climates.  There  are  numerous  varieties,  of  which  the 
following  are  the  principal  : — 

(1)  Gossypium  barbadense. — An  herbaceous  plant,  bear- 
ing a  yellow  flower,  and  attaining  a  height  of  4-5  m. 
(13-16  ft.).  A  variety  of  this  species  yields  the  Sea  Island 
cotton,  much  prized  on  account  of  the  great  strength, 
length,  and  lustre  of  its  fibres.  It  is  grown  in  the  North 
American  States  of  South  Carolina,  Georgia,  and  Florida, 
and  on  the  neighbouring  islands  of  the  West  Indies. 

(2)  Gossypium  hirsutum. — A  hairy,  herbaceous  plant, 
about  2  m.  high,  with  pale  yellow  or  almost  white  flowers. 
It  is  grown  in  the  States  of  Alabama,  Louisiana,  Texas, 
and  Mississippi. 


Fig-.  2. — Appearance  of  Cotton  under  the  Microscope. 

(3)  Gossypium  herbaceum. — A  small  herbaceous  plant, 
1  m.  high,  and  bearing  yellow  flowers.  Varieties  of  this 
species  are  grown  in  India,  China,  Egypt,  and  America. 
The  Madras,  Surat,  and  short-stapled  Egyptian  cotton, 
also  some  American  cottons,  are  obtained  from  this  species. 

(4)  Gossypium  peruvianum. — This  species,  a  native  of 
South  America,  grows  to  a  height  of  3-5  m.  (10-16  ft.),  and 
bears  a  yellow  flower.  It  yields  the  long-stapled  and 
much-esteemed  Peruvian  and  Brazilian  cottons. 

(5)  Gossypium  religiosum. — This  is  a  low  annual  shrub, 
about  1  m.  high,  and  bearing  a  yellow  flower.  It  is  grown 
in  China  and  India,  and  yields  the  so-called  Nankin 
cotton,  remarkable  for  its  tawny  colour. 

(6)  Gossypium  arboreum. — This  is  a  perennial  tree, 
growing  to  a  height  of  6-7  m.  (20-23  ft.),  and  bearing  red- 
dish-purple flowers.  It  is  a  native  of  India,  and  produces 
a  good  quality  of  cotton. 


COTTON. 


11 


Physical  Structure  of  Cotton. — If  raw  cotton  is  ex- 
amined under  the  microscope,  it  is  seen  to  consist  of  minute 
fibres.  Their  general  appearance  is  that  of  spirally- 
twisted  bands,  having  thickened  borders  and  irregular 
markings  on  the  surface  (Fig.  2).  In  the  better  qualities 
of  cotton,  such  as  Sea  Island,  the  spiral  character  is  less 
prominent.  Transverse  sections  of  the  fibres  show  them 
to  be  flattened  tubes,  having  comparatively  thick  walls  and 
a  small  central  opening  (Fig.  3). 

A  single  cotton  fibre  is  an  elongated,  tapering,  and 


collapsed  plant  cell,  the  thin  end  of  which  is  closed,  and 
the  other  (by  which  it  was  attached  to  the  seed)  irregularly 
torn.  Sometimes  broad  ribbon-like  fibres  may  be  noticed, 
which  are  remarkably  transparent,  and  possess  irregular 
folds.  Their  transverse  section  exhibits  no  central  open- 
ing (Fig.  4).  They  are  unripe  fibres,  in  which  no  separa- 
tion of  the  thin  cell  walls  has  yet  taken  place.  They 
refuse  to  be  dyed  like  ordinary  ripe  fibres,  and  appear 
occasionally  as  white  specks  in  indigo-  and  madder-dyed 
calicoes;  hence  the  name  of  dead  cotton  has  been  given 


Fig.  i. — Transverse  Sections  of  Unripe  Cotton  Fibre. 

to  them.  In  half-ripe  cotton  fibres  the  cell  walls  are  still 
so  closely  pressed  together  that  the  ultimate  central  canal 
is  indicated  in  a  transverse  section  only  by  a  fine  line. 
When  steeped  in  water,  however,  such  fibres  gradually 
swell  up  and  form  hollow  tubes.  Cotton  fibres  vary  in 
length  2*5-6  cm.  (1-2|  in.),  and  in  breadth  0'0l7-005  mm. 
(-0007--002  in.). 

The  spiral  character  of  the  fibre  makes  it  possible  to 
spin  exceeding  fine  yarn,  and  also  accounts  for  the  elastic 
character  of  calico  as  compared  with  linen,  the  fibres 


Fig.  3. — Transverse  Sections  of  Cotton  Fibre. 


12 


TEXTILE  FABRICS. 


of  which  are  stiff  and  straight.  The  microscopic  appear- 
ance of  cotton  serves  to  distinguish  it  from  other  vegetable 
and  animal  fibres. 

Chemical  Composition  of  Cotton. — The  substance  of  the 
cotton  fibre  is  called  Cellulose.  This  is  almost  universal 
in  vegetable  cells,  forming  the  so-called  ligneous  matter  or 
woody  fibre  of  plants,  but  whereas  in  woody  fibre  the  cellu- 
lose is  encrusted  with  a  large  proportion  of  foreign  matter 
— such  as  dried-up  sap,  resin,  etc. — in  the  cotton  fibre  it 
is  in  a  tolerably  pure  condition.  The  impurities  present 
amount  to  about  5  %,  this  being  the  loss  sustained  by 
raw  cotton  when  submitted  to  the  process  of  bleaching, 
the  main  object,  indeed,  of  which  is  the  total  removal  of 
these  impurities.  The  principal  bleaching  operation  con- 
sists in  boiling  the  cotton  with  a  solution  of  sodium  car- 
bonate or  hydrate.  From  the  dark  brown  solution  thus 
obtained,  acids  throw  down  a  voluminous  light  brown 
precipitate,  which,  when  washed  and  dried,  amounts  only 
to  about  0'5  %  of  the  weight  of  cotton  employed.  This 
precipitate  is  found  to  consist  of  the  following  organic 
substances  :  Pectic  acid,  brown  colouring  matter,  cotton 
wax,  fatty  acids  (margaric  acid)>  and  albuminous  matter. 
Pectic  acid  exists  in  the  largest  proportion,  and  it  is  not 
improbable  that  the  4'5  %  loss  by  bleaching  still  unac- 
counted for,  represents  certain  pectic  matters,  modified 
and  rendered  soluble  by  the  action  of  alkalis,  but  not 
precipitated  by  acids. 

In  addition  to  the  above-mentioned  impurities  of  the 
cell  wall,  the  raw  cotton  fibre  seems  to  be  covered  with  an 
exceedingly  delicate  membrane,  or  cuticle,  which  is  not 
cellulose.  If  cotton,  when  under  microscopical  observa- 
tion, be  moistened  with  an  ammoniacal  solution  of  cupric 
hydrate,  the  fibre  swells  up  under  its  influence,  whereas 
the  cuticle  is  unaffected  and  shows  itself  as  band-like 
strictures  or  rings  of  various  breadths.  If  a  drop  of  sul- 
phuric acid  be  then  added,  the  cellulose  separates  out  as  a 
gelatinous  mass,  which,  on  adding  a  drop  of  iodine  solu- 
tion, becomes  coloured  blue,  whereas  the  cuticle  is  coloured 
yellow.  By  moving  the  cover-glass  aside  a  little,  the 
cuticle  rings  are  seen  to  be  in  the  form  of  tubes,  possess- 
ing apparently  a  spiral  structure.  Some  observers  state 
that  during  the  bleaching  process  this  cuticle  is  removed, 


COTTON. 


13 


while  others  say  this  is  not  the  case.  The  standard  of 
moisture  in  raw  cotton  is  8*5  %,  so  that,  reckoning  the 
5  %  impurities  already  alluded  to,  one  may  consider  that 
raw  cotton  contains  86'5  %  of  pure  dry  cellulose. 

When  submitted  to  chemical  analysis,  cellulose  is  found 
to  be  composed  of  carbon,  hydrogen,  and  oxygen,  the  for- 
mula assigned  to  it  being  C6H10O5.  It  is  closely  allied 
in  composition  to  starch,  dextrin,  and  glucose,  and  is 
classed  along  with  them  as  a  carbo-hydrate.  It  is  colour- 
less, possesses  neither  taste  nor  smell,  and  has  a  density 
of  about  1*5.  If  heated  above  130°  C.  it  becomes  brown, 
and  begins  to  decompose.  In  contact  with  air  it  burns 
without  emitting  any  very  strong  odour,  a  fact  which 
may  sometimes  serve  to  distinguish  it  from  wool  and 
silk.  It  is  quite  insoluble  in  the  ordinary  solvents,  water, 
alcohol,  ether,  etc.,  but,  as  already  indicated,  it  dissolves 
in  an  ammoniacal  solution  of  cupric  hydrate;  from  this 
it  is  precipitated  by  acids  as  a  gelatinous  mass,  which, 
when  washed  with  alcohol,  forms  an  amorphous  white 
powder. 

Action  of  Mildew  on  Cotton. — Owing  to  its  comparative 
freedom  from  impurity,  cotton  may  be  stored  for  a  long 
period  without  undergoing  any  change,  more  especially  if 
it  is  bleached  and  kept  dry.  When,  however,  it  is  con- 
taminated with  added  foreign  organic  matter,  such  as 
starch,  gum,  etc.  (in  "  finished  "  calicoes),  and  then  ex- 
posed to  a  moist,  warm  atmosphere,  it  is  very  liable  gradu- 
ally to  become  tender  or  rotten.  This  is  owing  to  the 
growth  of  vegetable  organisms  of  a  very  low  order,  gener- 
ally called  "  mildew."  These  fungi  feed  upon  the  starchy 
matters  present,  inducing  their  decomposition,  and  after 
some  time  the  cotton  fibres  themselves  are  attacked.  The 
simultaneous  production  of  crenic,  humic,  ulmic,  and  other 
organic  acids  may  possibly  assist  somewhat  in  the  tender- 
ing process. 

Action  of  Frost  on  Cotton. — It  has  been  supposed  by 
some  that  wet  calico  is  tendered  when  it  is  frozen.  Al- 
though the  evidence  on  this  point  is  conflicting,  it  is  quite 
conceivable  that  the  crystallisation  might  act  injuriously 
in  a  mechanical  way,  and  that  the  atmospheric  ozone  might 
also  exercise  some  slight  destructive  influence.  The  popu- 
lar notion  probably  arises  from  the  fact  that  in  their  rigid 


14 


TEXTILE  FABRICS. 


state  the  cotton  fibres  are  readily  broken.  A  similar  fri- 
able condition  is  obtained  by  excessive  stiffening  with 
starch  or  gum. 

Action  of  Acids  on  Cotton. — Cold  dilute  mineral  acids 
have  little  or  no  action,  but  if  allowed  to  dry  upon  the 
cotton  they  gradually  become  sufficiently  concentrated  to 
corrode  and  tender  the  fibre.  The  physical  structure  of 
the  fibre  is  not  affected,  but  the  chemical  composition  of  the 
disintegrated  fibre  seems  to  be  somewhat  altered  :  it  con- 
tains more  oxygen  and  hydrogen.  The  same  corrosive 
action  soon  takes  place  if  cotton  impregnated  with  such 
acids  is  heated.  The  process  of  "  extracting  "  or  "  car- 
bonising" woollen  rags  containing  cotton  (destroying  and 
removing  the  cotton),  by  means  of  sulphuric  or  hydro- 
chloric acid,  is  founded  on  this  fact. 

The  action  of  strong  acids  varies  considerably  accord- 
ing to  the  nature,  concentration,  and  temperature  of  the 
acid,  as  well  as  the  duration  of  its  contact  with  the  fibre. 

Very  concentrated  sulphuric  acid  causes  cotton  to  swell 
up,  and  form  a  gelatinous  mass,  from  which,  on  the 
addition  of  water,  a  starch-like  substance  termed  Amyloid 
may  be  precipitated.  A  solution  of  iodine  colours  this 
amyloid  blue.  Vegetable  parchment  is  paper  (cellulose) 
superficially  changed  into  amyloid  by  a  short  steeping  in 
strong  sulphuric  acid  140°  Tw.  (Sp.  Gr.  1*7),  then  washing 
and  drying.  An  increased  affinity  for  basic  coal-tar 
colouring  matters  is  said  to  be  imparted  to  cotton  by  this 
treatment,  even  when  the  acid  is  diluted  to  84°  Tw.  (Sp. 
Gr.  1*42),  although  its  physical  aspect  then  remains  un- 
changed. Cotton  completely  disorganised  by  acid,  and 
obtained  as  a  fine  powder,  seems  to  contain  one  molecule  of 
water  more  than  ordinary  cellulose,  and  the  substance  thus 
produced  has  been  termed  Hydro-cellulose. 

If  the  concentrated  sulphuric  acid  is  allowed  to  act  for 
a  longer  time,  the  cotton  dissolves  with  the  formation  of 
a  different  substance  of  a  gummy  nature,  called  Dextrin 
(C6H10O5) ;  when  the  solution  is  diluted  with  water  and 
boiled  for  some  time,  this  dextrin  is  further  changed  into 
Glucose  (C6H1206). 

If  cotton  be  heated  with  strong  nitric  acid  it  is  entirely 
decomposed,  producing  oxalic  acid  and  an  oxidised  cellu- 
lose soluble  in  alkalis.    By  the  action  of  cold  concentrated 


COTTON. 


15 


nitric  acid,  or,  better  still,  a  mixture  of  strong  nitric  and 
sulphuric  acids,  cellulose  is  changed  into  so-called  Nitro- 
cellulose. The  physical  structure  of  the  cotton  remains 
the  same,  although  increased  in  weight  by  more  than  5  %, 
but  its  chemical  composition  and  properties  are  very  much 
altered,  certain  elements  of  the  nitric  acid  having  replaced 
a  greater  or  less  proportion  of  the  hydrogen  of  the  cellu- 
lose. The  most  highly  nitrated  compound  is  Pyroxylin, 
or  Gun-cotton  (C12H14(NO2)6O10),  produced  by  the  short 
action  of  a  very  concentrated  mixture  of  acids;  it  is  very 
explosive,  and  insoluble  in  alcohol  and  ether.  The  less 
nitrated  product,  obtained  by  the  longer  action  of  more 
dilute  acids,  forms  the  so-called  Soluble  Pyroxylin.  Its 
solution  in  a  mixture  of  ether  and  alcohol  constitutes 
Collodion,  which  on  evaporation  leaves  the  pyroxylin  as 
a  thin,  transparent,  horny  film,  insoluble  in  water.  It 
was  long  ago  noticed  by  Kuhlmann  that  gun-cotton  had  an 
increased  affinity  for  colouring  matters,  but  no  practical 
use  has  been  made  of  the  fact. 

Strong  hydrochloric  and  phosphoric  acids  behave  to- 
wards cotton  like  sulphuric  acid,  but  their  action  is  less 
energetic.  The  ultimate  product  of  the  action  of  hydrochloric 
acid  on  cotton  is  the  same  as  that  given  by  sulphuric  acid,  but 
there  is  r.o  intermediate  formation  of  amyloid. 

Solutions  of  tartaric,  citric,  and  oxalic  acids  have  no 
destructive  action  on  cotton  if  it  is  simply  steeped  in 
the  liquid;  but  if  cotton  saturated  with  a  solution  con- 
taining 2  %  of  any  of  the  above  acids  is  dried  and  heated 
for  an  hour  to  100°  C,  it  becomes  slightly  tendered.  With 
4  %  solutions  the  destructive  action  is  very  decided  at 
100°  C,  and  perceptible  even  at  80°  C.  Oxalic  acid  has  the 
most  injurious  effect  in  this  respect.  If  the  acid  solutions 
are  thickened  with  gum  or  starch,  and  if  steaming  be 
substituted  for  a  dry  heat,  the  corrosive  action  in  each 
case  is  less  marked,  so  that  in  the  ordinary  practice  of 
the  calico-printer,  who  frequently  uses  steam-colours  con- 
taining 4  %  or  more  of  the  above  acids,  there  is  little  to 
fear.  Still,  it  is  well  to  bear  in  mind  that  even  organic 
acids  cannot  under  all  circumstances  be  applied  to  cotton 
with  impunity. 

Acetic  acid  may  be  considered  as  having  no  perceptible 
action  on  cotton. 


16 


TEXTILE  FABRICS. 


Action  of  Alkalis  on  Cotton. — Weak  solutions  of  caustic 
potash  or  soda,  when  used  cold,  have,  under  ordinary  cir- 
cumstances, no  action  on  cotton,  although  long-continued 
and  intermittent  steeping  and  exposure  to  air  tender  the 
fibre.  Cotton  may  even  be  boiled  for  several  hours  with 
weak  caustic  alkalis,  if  care  be  taken  that  it  remains 
steeped  below  the  surface  of  the  solution  during  the  whole 
operation,  but  otherwise  it  is  very  liable  to  become  rotten, 
especially  if  the  exposed  portions  are  at  the  same  time 
under  the  influence  of  steam.  Such  exposure  is  to  be 
guarded  against  during  certain  of  the  operations  in  bleach- 
ing cotton  fabrics.  The  tendering  action  is  probably  due 
to  oxidation.  It  is  worthy  of  note  that  the  disorganised 
fibre  (oxy-cellulose)  possesses  an  increased  attraction  for 
basic  coal-tar  colouring  matters. 

In  the  case  of  raw  cotton,  the  action  of  boiling  with 
weak  caustic  alkalis  is  simply  to  remove  those  natural 
impurities  already  referred  to,  which  cause  it  to  be  water- 
repellent,  and  therefore  difficult  to  wet  by  mere  steeping 
in  cold  water. 

The  action  of  strong  solutions  of  caustic  potash  or 
soda  is  very  remarkable.  If  a  piece  of  calico  is  steeped 
for  a  few  minutes  in  a  solution  of  caustic  soda,  marking 
about  50°  Tw.  (Sp.  Gr.  1*25),  it  assumes  quite  a  gelatinous 
and  translucent  appearance;  when  taken  out  and  washed 
free  from  alkali,  it  is  found  to  have  shrunk  considerably, 
and  become  much  closer  in  texture.  If  a  single  fibre  of 
the  calico  thus  treated  be  examined  under  the  microscope, 
it  is  seen  to  have  lost  all  its  original  characteristic  ap- 
pearance ;  it  has  no  superficial  markings,  and  is  no  longer 
flat  and  spirally  twisted,  but  seems  now  to  be  thick, 
straight,  and  transparent.  A  transverse  section  shows  it 
to  be  cylindrical,  while  the  cell  walls  have  considerably 
thickened,  and  the  central  opening  is  diminished  to  a  mere 
point  (Fig.  5).  Many  years  ago  a  Lancashire  calico- 
printer,  John  Mercer,  discovered  that  calico  treated  in  the 
above  manner  was  not  only  stronger  than  before,  but  had 
also  acquired  an  increased  attraction  for  colouring  mat- 
ters. Hoping  to  apply  the  process  with  advantage  pre- 
paratory to  dyeing,  he  patented  it.  Cotton  thus  treated 
was  at  that  time  said  to  be  Mercerised,  but  that  term  is 
now  applied  to  cotton  or  cotton  materials  which  are 


COTTON. 


17 


treated  with  soda  lye  under  a  tension  which  prevents  the 
shrinkage  above  mentioned,  or  are  afterwards  stretched 
to  counteract  that  shrinkage.  When  dyed  in  the  indigo- 
vat,  mercerised  calico  requires  only  one  dip  to  produce  as 
deep  a  shade  of  blue  as  can  be  obtained  on  ordinary  calico 
only  after  five  or  six  dips.  Again,  if  a  piece  of  ordinary 
and  a  piece  of  mercerised  calico  be  dyed  alizarin  red, 
making  all  other  conditions  (time,  temperature,  quantity 
of  Alizarin,  etc.)  the  same  in  both  cases,  the  mercerised 
cloth  will  be  found  to  have  a  much  fuller  and  richer  colour 
than  the  other.  Similar  differences  in  depth  of  shade  are 
noticed  with  other  colours.  The  process,  however,  was 
never  adopted  in  general  practice  as  a  means  of  saving 
dyestuffs,  but  in  more  recent  years  has  been  largely 
adopted  for  giving  a  brilliant  lustre  to  the  cotton. 

Caustic  ammonia  in  aqueous  solution,  whether  strong 
or  weak,  has,  under  all  circumstances,  no  action  on  cotton. 


Fig.  5. — Transverse  Sections  of  Cotton  Fibre  after  Treatment  with 
Caustic  Soda. 

Dry  cotton  is  said  to  absorb  115  times  its  bulk  of  ammonia 
gas.  Solutions  of  the  carbonates  of  potash,  soda  or  am- 
monia, silicate  of  soda,  borax,  and  soap,  have  practically 
no  action  on  cotton.  There  is  a  case  on  record,  however, 
in  which  calico  impregnated  with  silicate  of  soda,  and 
shipped  from  England  to  South  Africa,  was  found,  after 
having  been  packed  in  bales  for  two  years,  to  have  be- 
come tender.  Examination  showed  that  the  silicate  of 
soda  had  decomposed  with  formation  of  silicic  acid  and 
carbonate  of  soda,  and  it  was  concluded  that  the  tendering 
was  due  partly  to  the  long-continued  action  of  the  car- 
bonate of  soda  on  the  cotton,  and  partly  to  disruption  of 
the  fibres  by  the  expansive  force  of  the  crystallisation  of 
the  carbonate  of  soda  formed  within  them.  The  explana- 
tion is  not  altogether  satisfactory,  since  it  was  found 
impossible  to  produce  the  same  effects  artificially.  Pro- 
bably it  was  a  case  of  oxidation  of  the  fibre.  Whatever 
may  have  been  the  real  cause,  it  is  well  to  bear  in  mind  that 

B 


18 


TEXTILE  FABRICS. 


under  exceptional  conditions  like  those  mentioned,  even 
apparently  harmless  salts  may  tender  the  cotton  fibre. 

Action  of  Lime  on  Cotton. — Milk  of  lime,  even  at  a 
boiling  heat,  has  little  or  no  action  upon  cotton  so  long 
as  the  latter  is  steeped  below  the  surface  of  the  liquid,  but 
if  it  is  at  the  same  time  exposed  to  the  action  of  air  or 
steam,  it  becomes  much  tendered  by  oxidation  of  the  fibre. 
Such  exposure  must  be  avoided  in  cotton-bleaching. 

Action  of  Chlorine  and  Hypochlorites  on  Cotton. — 
Cotton  is  quickly  tendered  if  exposed  to  moist  chlorine 
gas,  especially  in  strong  sunlight.  The  action  may  be  due 
partly  to  the  direct  action  of  chlorine  upon  the  fibre,  one 
portion  combining  with  and  another  replacing  some  of  its 
hydrogen,  partly  to  the  destructive  action  of  the  hydro- 
chloric acid  thus  produced,  and  partly  to  oxidation.  Solu- 
tions of  hypochlorites  (bleaching  powder,  etc.)  tender 
cotton  more  or  less  readily,  according  to  the  strength  and 
temperature  of  the  solutions  and  the  duration  of  their 
action.  Even  a  very  weak  solution  of  bleaching-powder  will 
tender  cotton  if  the  latter  be  boiled  with  it;  but  when  used 
cold,  even  if  it  be  at  the  same  time  exposed  to  the  air, 
the  destructive  action  is  inappreciable,  and  confined  merely 
to  bleaching  the  natural  colouring  matter  of  the  cotton. 
If  a  piece  of  calico  is  moistened  with  a  solution  of  bleach- 
ing-powder to  5°  Tw.  (Sp.  Gr.  .1  025),  then  exposed  to  the 
air  for  about  an  hour,  and  washed,  it  will  be  found  to 
have  acquired  an  attraction  for  basic  coal-tar  colouring 
matters  similar  to  that  possessed  by  the  animal  fibres. 
Cotton  thus  treated  also  decomposes  directly,  the  normal 
salts  of  aluminium,  iron,  etc.,  attracting  metallic  oxide. 
Experiment  has  shown  that  this  remarkable  change  is  due 
to  the  action  of  the  hypochlorous  acid  liberated  by  the 
carbonic  acid  of  the  air.  The  cotton  thereby  becomes 
chemically  changed  to  what  has  been  called  by  Witz,  its 
discoverer,  Oxy-cellulose. 

Action  of  Metallic  Salts  on  Cotton. — Under  ordinary 
circumstances,  solutions  of  neutral  salts  have  no  action  on 
cotton ;  even  those  of  acid  salts  have  no  appreciable  effect 
if  the  cotton  be  merely  steeped  in  them  while  cold ;  but  if 
boiled  with  them  the  effect  is  similar  to  that  of  the  free 
acids,  though  slightly  less  marked.  If  cotton  is  impreg- 
nated with  solutions  of  the  salts  of  the  earths  and  heavy 


COTTON. 


19 


metals,  then  dried,  and  heated  or  steamed,  the  salts  are 
readily  decomposed  ;  a  basic  salt  is  precipitated  on  the 
fibre,  and  the  liberated  acid  affects  the  fibre  according  to 
the  nature  and  strength  of  the  salt  solution  employed. 

The  use  of  aluminium  chloride,  which  was  at  one  time 
recommended  for  the  purpose  of  destroying  the  cotton  in 
rags  containing  cotton  and  wool  ("  extracting  also  the 
application  of  the  "  topical  "  or  "  steam  colours,"  and  the 
"  mordanting  "  process  employed  by  the  calico-printer, 
are  all  based  upon  the  above  facts. 

Action  of  Colouring  Matters  on  Cotton. — With  few  ex- 
ceptions, colouring  matters  are  not  directly  attracted  from 
their  solutions  by  the  cotton  fibre,  hence  it  is  not  readily 
dyed,  and  special  means  of  preparing  it  to  receive  the 
dyes  have  to  be  adopted  in  most  cases  (mordanting). 
The  reason  of  this  inert  character  of  cotton  is  not  yet 
satisfactorily  explained;  probably  both  its  chemical  and 
physical  structure  have  an  influence  in  the  matter. 


20 


CHAPTER  II. 

FLAX,  JUTE,  AND  CHINA  GRASS. 

The  Flax  Plant. — The  term  "  flax  "  designates  the  flax  or 
linen  fibre  and  also  the  plant  from  which  it  is  obtained. 
Linen  fibre  consists  of  the  bast  cells  of  certain  species 
of  the  genus  Linum,  more  particularly  Linum  usitatissi- 
mum,  a  plant  belonging  to  the  natural  order  Linacece.  It 
is  an  herbaceous  plant,  having  a  thin,  spindle-shaped  root, 
a  stem  usually  branched  at  the  top,  smooth  lanceolate 
leaves,  and  bright  blue  flowers,  and  is  cultivated  in  nearly 
all  parts  of  Europe. 

The  time  of  sowing  varies  in  different  countries  from 
February  to  April,  consequently  the  time  of  harvest  also 
varies,  and  may  be  from  June  to  September. 

If  the  object  of  the  farmer  is  to  obtain  good  fibre,  and 
not  seed  for  re-sowing,  the  plant  is  gathered  before  it  is 
fully  matured — namely,  when  the  lower  portion  of  the 
stem  (about  two-thirds  of  the  whole)  has  become  yellow, 
and  the  seed  capsules  are  just  changing  from  green  to 
brown.  At  this  stage  the  plants  are  carefully  pulled  up. 
If  they  are  left  in  the  ground  till  the  plant  is  fully  ripe 
and  the  whole  stem  is  yellow,  the  fibre  obtained  will  be 
more  stiff  and  coarse. 

The  freshly-pulled  flax  is  at  once  submitted  to  the 
process  of  "  rippling,"  which  has  for  its  object  the  re- 
moval of  the  seed  capsules.  This  operation  is  performed 
by  hand,  by  drawing  successive  bundles  of  flax-straw 
through  the  upright  prongs  of  large,  fixed  iron  combs,  or 
"  ripples."  If  the  pulled  flax  has  been  dried  and  stored, 
the  removal  of  the  seeds  is  usually  effected  by  the  seeding- 
machine,  which  consists  essentially  of  a  pair  of  iron 
rollers,  between  which  the  flax-straw  is  passed. 

Betting. — The  most  important  operation  in  separating 
the  fibre  is  that  of  "  retting,"  the  object  of  which  is  to 
decompose  and  render  soluble  by  fermentation,  as  well  as 


FLAX,  JUTE,  AND   CHINA  GRASS. 


21 


to  remove,  certain  adhesive  substances  which  bind  the  bast 
fibres  not  only  to  each  other,  but  also  to  the  central  woody 
portion  of  the  stem,  technically  termed  the  "  shrive," 
"  shore/'  or  "  boon." 

The  various  moles  of  retting  may  be  classified  as  : — 

(1)  Cold-water  retting,  which  may  be  carried  out  with 
running  or  with  stagnant  water. 

(2)  Dew  retting. 

(3)  Warm-water  retting. 

Cold-water  Retting. — The  best  system  of  retting  in 
running  water  is  said  to  be  practised  in  the  neighbourhood 
of  Courtrai,  in  Belgium,  where  the  water  of  the  sluggish 
river  Lys  is  available.  The  bundles  of  flax  straw  are 
packed  vertically  in  large  wooden  crates  lined  with  straw. 
Straw  and  boards  are  afterwards  placed  on  the  top,  and 
the  crate  thus  charged  is  anchored  in  the  stream  and 
weighted  with  stones,  so  that  it  is  submerged  a  few  inches 
below  the  surface.  In  a  few  days  fermentation  begins, 
and  as  it  proceeds  additional  weight  must  be  added  from 
time  to  time,  in  order  to  prevent  the  rising  of  the  crates 
through  the  evolution  of  gas.  As  a  rule,  after  steeping  for 
a  short  period,  the  flax  is  removed  from  the  crates,  and 
set  up  in  hollow  sheaves  to  dry ;  it  is  then  repacked  in 
the  crates,  and  again  steeped  until  the  retting  is  com- 
plete. According  to  the  temperature,  quality  of  flax,  etc., 
the  duration  of  the  steeping  may  be  from  10-20  days.  The 
end  of  the  process  must  be  accurately  determined  by  oc- 
casionally examining  the  appearance  of  the  stems,  and 
applying  certain  tests,  The  flax  bundles  should  feel  soft, 
and  the  stems  should  be  covered  with  a  greenish,  slime, 
easily  removed  by  passing  them  between  the  finger  and 
thumb ;  when  bent  over  the  forefinger  the  central  woody 
portion  should  spring  up  readily  from  the  fibrous  sheath. 
If  a  portion  of  the  fibre  is  separated  from  the  stem  and 
suddenly  stretched,  it  should  draw  asunder  with  a  soft, 
not  a  sharp,  sound.  When  the  retting  is  complete,  the  flax 
is  carefully  removed  from  the  crates  and  set  up  in  sheaves 
to  dry. 

Stagnant-water  retting  is  the  method  usually  adopted 
in  Ireland  and  Russia.  The  flax  is  steeped  in  ponds,  pre- 
ferably situated  near  a  river,  and  provided  with  suitable 
arrangements  for  admitting  and  running  off  the  water. 


22 


TEXTILE  FABRICS. 


This  mode  of  retting  is  more  expeditious  than  when  run- 
ning water  is  employed,  because  the  organic  matters  re- 
tained in  the  water  very  materially  assist  the  fermenta- 
tion ;  there  is,  however,  always  a  danger  of  "  over-retting," 
that  is,  the  fermentation  may  become  too  energetic,  in 
which  case  the  fibre  itself  is  attacked  and  more  or  less 
weakened.  This  danger  is  minimised#by  occasionally 
changing  the  water  during  the  steeping  process.  The 
quality  of  the  water  employed  in  retting  is  of  considerable 
importance ;  pure  soft  water  is  the  best,  calcareous  water 
being  altogether  unsuitable.  The  waste  water,  being 
strongly  impregnated  with  decomposing  organic  matter, 
poisons  the  streams  into  which  it  may  run,  and  destroys 
the  fish ;  but  it  possesses  considerable  value  as  a  liquid 
manure. 

After  retting  in  stagnant  water,  the  flax  is  drained, 
then  thinly  spread  on  a  field,  where  it  is  left  for  a  week 
or  more,  and  occasionally  turned  over.  This  process  is 
termed  "  spreading  "  or  "  grassing."  Its  object  is  not 
merely  to  dry  the  flax,  but  to  allow  the  joint  action  of 
dew,  rain,  air,  and  sunlight  to  complete  finally  the  destruc- 
tion and  removal  of  the  adhesive  substances  already 
alluded  to.  After  a  few  days'  exposure  the  stems  begin 
to  "  bow,"  the  fibrous  sheath  separates  more  or  less  from 
the  woody  centre,  and  the  latter  becomes  friable. 

Dew  retting  consists  in  spreading  the  flax  on  the  field 
and  exposing  it  to  the  action  of  the  weather  for  6-8 
weeks,  without  any  previous  steeping.  Damp  weather  is 
the  most  suitable  for  this  method,  since  all  fermentation 
ceases  if  the  flax  becomes  dry.  Dew  retting  is  practised 
largely  in  Russia  and  in  some  parts  of  Germany. 

Warm-water  retting  was  a  system  recommended  in 
1847  by  R.  B.  Schenck.  It  consists  in  steeping  the  closely- 
packed  flax  bundles  in  covered  wooden  vats,  filled  with 
water  heated  to  25°-35°  C.  By  this  means  the  fermenta- 
tion is  much  accelerated,  and  the  operation  is  completed 
in  2-3  days ;  the  process  seems,  however,  to  have  met  with 
only  limited  success. 

Chemical  retting,  the  process  recommended  by  R.  Baur, 
may  be  mentioned.  It  consists  in  first  squeezing  the 
fresh  or  dried  flax  straw  between  rollers,  and  then  steep- 
ing it  in  water  till  the  latter  ceases  to  be  coloured  yellow. 


FLAX,  JUTE,  AND   CHINA  GRASS. 


23 


It  is  next  drained  and  steeped  for  1-2  days  in  dilute  hydro- 
chloric acid  (3  kg.  concentrated  HC1  per  100  kg.  flax), 
until  the  bast  fibres  can  be  readily  separated.  The  acid 
liquid  is  then  run  off,  and  the  flax  is  well  washed  with 
slightly  alkaline  water,  or  such  as  contains  a  little  chalk. 
A  further  treatment  with  dilute  bleaching  powder  solution 
to  dissolve  away  still  adhering  woody  matter,  and  a  final 
washing,  complete  the  process.  A  well-retted  flax  is  said 
to  be  thus  obtained  in  the  course  of  a  few  days  only. 

Chemist  ry  of  Betting. — Experiments  by  Kolb  indicate 
that  the  adhesive  matter  which  cements  the  flax  fibres 
together  is  essentially  a  substance  called  pectose.  During 
the  retting  process  the  fermentation  decomposes  this  in- 
soluble pectose,  and  transforms  it  into  soluble  pectine, 
and  insoluble  pectic  acid.  The  former  is  washed  away, 
the  latter  remains  attached  to  the  fibre. 

Breaking. — The  next  operation  is  to  remove  the  woody 
centre  from  the  retted  and  dried  flax,  after  which  the 
fibres  must  be  separated  from  each  other.  It  is  rather 
beyond  the  scope  of  this  manual  to  give  more  than  a 
general  account  of  the  nature  of  the  various  mechanical 
operations  for  effecting  this.  They  comprise  "  breaking/ 1 
"  scutching/'  and  "  hackling." 

The  first  operation  aims  at  breaking  up  the  brittle 
woody  centre  of  the  flax  into  small  pieces,  by  threshing 
it  with  an  indented  wooden  mallet,  or  by  crimping  it  with 
a  many-bladed  "  braque."  The  operation  is  now  exten- 
sively done  by  machinery,  the  flax  being  passed  through  a 
series  of  fluted  rollers. 

Scutching. — In  this  process  handfuls  of  the  flax  are 
beaten  with  a  broad  wooden  scutching-blade ;  the  particles 
of  woody  matter  adhering  to  the  fibres  are  thus  detached ; 
and  the  bast  is  partially  separated  into  its  constitutent 
fibres.  Scutching  is  also  performed  by  machinery.  The 
waste  fibre  obtained  is  called  "  scutching  tow,"  or 
"  codilla." 

Hackling. — The  subsequent  hackling,  or  heckling,  has 
for  its  object  a  still  further  separation  of  the  fibres  into 
their  finest  filaments,  by  combing.  When  done  by  hand,  a 
bundle  of  flax  is  drawn,  first  one  end  and  then  the  other, 
through  a  succession  of  fixed  upright  iron  combs  or 
"  hackles  "  of  different  degrees  of  fineness,  beginning  with 


TEXTILE  FABRICS. 


the  coarsest.  When  machinery  is  used,  the  flax  is  held 
against  hackles  fixed  on  moving  belts  or  bars  or  on  the 
circumference  of  revolving  cylinders.  The  product  of  the 
operation  is  twofold,  namely,  "  line  "  and  "  tow  "  ;  the 
former  consist  of  the  long  and  more  valuable  fibres,  the 
latter  of  those  which  are  short  and  more  or  less  tangled. 

Flax-line. — The  appearance  of  flax-line  is  that  of  long, 
fine,  soft,  lustrous  fibres,  varying  in  colour  from  the  yel- 
lowish-buff of  the  Belgian  product  to  the  dark  greenish- 
grey  of  Russian  flax.  This  difference  in  colour  is  chiefly 
owing  to  the  system  of  retting  adopted.  Flax  retted  in 
running  water  has  a  more  or  less  pale  yellowish-buff 


colour,  while  that  retted  in  stagnant  water  possesses  a 
greyish  colour,  probably  because  of  the  presence  of  the 
decomposing  organic  matter  in  the  water. 

Physical  Structure  and  Properties  of  Flax. — Examined 
under  the  microscope,  a  single  flax  fibre  appears  as  a  long, 
straight,  transparent  tube,  often  striated  longitudinally 
(Fig.  6);  it  possesses  thick  walls,  and  an  excessively  minute 
central  canal.  At  irregular  intervals  it  is  slightly  dis- 
tended, and  at  these  points  faint  transverse  markings  may 
be  detected.  When  examined  with  high  powers,  they  seem 
to  consist  of  a  succession  of  very  minute  fissures,  and,  ac- 
cording to  Vetillart,  are  simply  breaks,  or  wrinkles,  pro- 
duced by  bending  of  the  fibre,  and  not  cell  divisions,  or 
nodes,  as  frequently  stated.  Fibres  which  have  been  vigor- 
ously rubbed  between  the  fingers,  or  have  been  subjected 
to  the  lengthened  disintegrating  action  of  alkalis,  exhibit 
well-marked  longitudinal  fissures,  and  the  broken  end  of  a 


Fig.  6. — -Flax  Fibre  under  the  Microscope. 


FLAX,  JUTE,  AND   CHINA  GRASS. 


25 


well-worn  fibre  presents  the  aspect  of  a  bundle  of  fibrils. 
These  appearances  evidently  indicate  that  the  cell  wall  of 
the  linen  fibre  possesses  a  fibrous  structure. 

The  average  length  of  a  single  fibre  is  25-30  mm.  (1-1-10 
in.),  and  the  average  breadth  0'020-0'025  mm.  (0-008-00082 
in.).  In  transverse  section,  the  linen  fibre  shows  a  more 
or  less  rounded  polygonal  contour. 

The  chief  physical  characteristics  of  the  linen  fibre, 
when  freed  from  all  encrusting  material,  are  its  snowy 
whiteness,  silky  lustre,  and  great  tenacity.  This  last  fea- 
ture is  no  doubt  owing  to  its  fibrous  texture  as  well  as  to 
the  thickness  of  the  cell  walls.  Its  straight,  even,  pris- 
matic, and  transparent  character  accounts  largely  for  the 
lustre. 

Linen  is  hygrometric  to  about  the  same  degree  as 
cotton,  and  contains,  when  air-dry,  12  %  of  moisture. 
As  it  is  a  much  better  conductor  of  heat,  it  feels  colder 
than  cotton,  and  is  also  less  pliant  and  less  elastic. 

Chemical  Composition  of  Flax. — Treated  with  sulphuric 
acid  and  iodine  solution,  the  thick  cell  wall  is  coloured 
blue,  while  the  secondary  deposits,  immediately  enclosing 
the  central  canal,  acquire  a  yellow  colour.  The  linen  fibre 
consists,  therefore,  essentially  of  cellulose,  but  in  its  raw 
unbleached  state  it  is  mixed  with  about  15-30  %  of  foreign 
substances,  chief  among  which  is  pectic  acid.  Fatty  mat- 
ter, to  the  extent  of  about  5  %,  colouring  matter,  and 
other  substances  not  investigated,  are  also  present. 

Action  of  Chemicals  on  Flax. — Being  cellulose,  the  ac- 
tion of  various  chemical  agents  on  pure  linen  fibre  is 
much  the  same  as  on  cotton,  but,  generally  speaking,  linen 
is  more  susceptible  to  disintegration,  especially  under  the 
influence  of  caustic  alkalis,  calcium  hydrate,  and  strong 
oxidising  agents,  such  as  chlorine,  hypochlorites,  etc. 

As  to  the  action  of  these  agents  on  the  encrusting 
materials  of  retted  flax,  boiling  solutions  of  caustic  and 
carbonated  alkalis  saponify  and  remove  the  fatty  matter, 
and  also  decompose  the  pectic  acid  and  any  pectose  which 
may  have  escaped  the  action  of  the  retting  process.  Under 
their  influence  the  insoluble  pectic  acid  is  changed  into 
metapectic  acid,  which  at  once  unites  with  the  alkali  to 
form  a  soluble  compound.  By  successive  boiling  with 
alkali  the  fibre,  entirely  loses  its  brownish  colour,  and 


26 


TEXTILE  FABRICS. 


retains  only  a  pale  grey  shade,  readily  bleached  by  hypo- 
chlorites. The  system  of  bleaching  linen  is  based  on  these 
reactions. 

Flax  (retted  in  running  or  stagnant  water)  is  capable  of 
being  well  bleached.  Under  the  influence  of  boiling  alkalis 
it  always  assumes  a  lighter  colour,  and  when  submitted  to 
the  reducing  action  of  stannous  chloride  it  acquires  a 
yellowish  tint.  Dew-retted  flax,  on  the  contrary,  bleaches 
with  much  difficulty.  When  boiled  with  alkalis  it  be- 
comes darker,  and  stannous  chloride  has  little  or  no  effect 
on  it.  These  reactions  may  serve  to  discover  by  which 
process  the  fibre  has  been  retted. 

Linen  fibre  is  dyed  even  less  readily  than  cotton,  a 
fact  which,  although  well  known  to  dyers,  has  not  yet  been 
satisfactorily  explained.  Its  physical  structure  and  the 
possible  presence  of  pectic  matters  no  doubt  exercise  some 
restraining  influence. 

Jute. — This  consists  of  the  bast  fibres  of  various  species 
of  Corchorus  (G.  olitorius,  G.  capsularis,  etc.),  belonging 
to  the  family  of  the  Tiliacece,  and  is  mainly  cultivated 
in  Bengal.  The  fibre  is  separated  from  the  plant  by  pro- 
cesses similar  to  those  employed  in  obtaining  the  flax  fibre, 
namely,  retting,  beating,  washing,  drying,  etc.  The  raw 
fibre,  as  exported,  consists  of  the  upper  five-sixths  of  the 
isolated  bast,  and  occurs  in  lengths  of  about  7  ft.  Under 
the  microscope  it  is  seen  to  consist  of  bundles  of  stiff, 
lustrous,  cylindrical  fibrils,  having  irregularly-thickened 
walls,  and  a  comparatively  large  central  opening.  The 
colour  of  the  fibre  varies  from  brown  to  silver-grey.  It 
is  distinguished  from  flax  by  being  coloured  yellow,  under 
the  influence  of  sulphuric  acid  and  iodine  solution. 

According  to  Cross  and  Bevan,  the  substance  of  the  jute 
fibre  is  not  cellulose,  but  a  peculiar  derivative  of  it,  to 
which  the  name  bastose  has  been  given.  Under  the  influ- 
ence of  chlorine,  a  chlorinated  compound  is  produced, 
which,  when  submitted  to  the  action  of  sodium  sulphite, 
develops  a  brilliant  magenta  colour.  This  colour  reaction 
is  also  exhibited  by  tannin-mordanted  cotton,  with  which 
jute  shows  great  similarity;  this  is  further  exemplified  by 
the  fact  that  jute  can  be  readily  dyed  in  a  direct  manner 
with  basic  colouring  matters. 

Jute  may  be  considered  as  consisting  of  cellulose,  a  por- 


FLAX,  JUTE,   AND   CHINA  GRASS. 


27 


tion  of  which  has  become  more  or  less  modified  through- 
out its  mass  into  a  tannin-like  substance.  Alkalis  actually 
resolve  jute  into  insoluble  cellulose  and  soluble  bodies 
allied  to  the  tannin  matters.  Further,  when  large  masses 
of  jute  are  allowed  to  lie  in  a  damp  state,  the  substance  of 
the  fibre  is  decomposed  into  two  groups  of  bodies,  namely, 
acids  of  the  pectic  class,  and  tannin-like  substances. 

Acids,  notably  mineral  acids,  even  at  low  temperatures, 
readily  disintegrate  jute,  resolving  it  into  soluble  sub- 
stances. This  destructive  action  of  acids  must  be  speci- 
ally borne  in  mind  by  the  dyer  and  bleacher  of  jute. 
Strong  solutions  of  hypochlorites  produce  the  chlorinated 
compound  above  alluded  to,  and  there  is  then  always  a 
danger  of  the  fibre  being  disintegrated  by  subsequent 
manufacturing  operations,  as  steaming.  Weak  solutions 
bleach  the  fibre  to  a  pale  cream  colour,  at  the  same  time 
oxidising  it,  and  thus  forming  compounds  which  precipi- 
tate soluble  calcium  salts.  In  bleaching  jute,  weak  sodium 
hypochlorite  should  be  used  in  preference  to  ordinary 
bleaching  powder  (calcium  hypochlorite),  since  the  pres- 
ence of  soda  prevents  the  formation  both  of  the  chlorinated 
fibre  and  of  insoluble  calcium  compounds.  By  thoroughly 
impregnating  the  bleached  fibre  with  sodium  bisulphite, 
and  drying  at  80°-100°  C,  the  colour  is  still  further  im- 
proved through  the  action  of  the  disengaged  sulphurous 
acid ;  the  neutral  sodium  sulphite  remaining  in  the  fibre 
prevents  its  oxidation  and  disintegration  under  the  in- 
fluence of  ordinary  atmospheric  conditions,  and  even 
steaming.  Jute  is  readily  bleached  by  the  successive  action 
of  permanganates  and  sulphurous  acid.  The  loss  of 
weight  experienced  by  jute  in  bleaching  may  vary  from 
2-8  %,  according  to  the  method  employed.  The  standard 
of  moisture  is  13*75  %. 

China  Grass. — This  fibre,  also  called  Rhea,  Ramie,  etc., 
consists  of  the  bast  cells  of  Boehmeria  nivea  (Urtica 
nivea),  a  perennial  shrub  belonging  to  the  nettle  family, 
Urticacece.  The  plant  grows  abundantly  in  India,  China, 
Japan,  and  the  Eastern  Archipelago  generally.  The 
native  methods  of  splitting  and  scraping  the  plant  stems, 
steeping  in  water,  etc.,  are  tedious  and  expensive,  while 
the  ordinary  retting  process  is  not  thoroughly  effective, 
because  of  the  succulent  nature  of  the  stem,  and  the  large 


28 


TEXTILE  FABRICS, 


amount  and  acridity  of  the  gummy  matters,  which  rapidly 
coagulate  and  become  insoluble  on  exposure  to  air.  There 
are  now  two  or  three  mechanical  methods  of  decorticating 
the  fibre  which  promise  success.  The  English  processes 
consist  of  mechanical  scrapers,  while  French  experimenters 
are  more  in  favour  of  high  pressure  kier  treatment. 

The  chief  characteristics  of  the  fibre  are  its  excessive 
strength  and  durability,  fineness,  silky  lustre,  and  pure 
white  colour.  Sulphuric  acid  and  iodine  solution  colour 
it  blue,  hence  it  seems  to  consist  essentially  of  cellulose. 
Under  the  microscope  the  fibres  appear  stiff  and  straight, 
the  cell  walls  exhibiting  a  fibrous  texture,  and  varying 
in  thickness  in  different  parts  of  the  fibre. 


29 


CHAPTER  III. 

WOOL. 

Varieties  of  Wool. — The  term  wool  describes  the  hairy 
covering  of  several  species  of  mammalia,  more  especially 
that  of  the  sheep.  It  differs  from  hair,  of  which  it  may 
be  regarded  as  a  variety,  by  being,  as  a  rule,  more  flexible, 
elastic,  and  curly,  and  because  it  possesses  certain  details 
of  surface-structure  which  enable  it  to  be  more  readily 
matted  together. 

Many  mammalia  have  both  wool  and  hair,  and  it  is 
probable  that  this  has  also  been  the  case  with  the  sheep 
in  its  original  wild  state,  but  under  the  influence  of 
domestication  the  rank  hairy  fibres  have  largely  disap- 
peared, while  the  soft  under-wool  round  their  roots  has 
been  singularly  developed.  The  sheep  was  domesticated  at 
so  early  a  date — as  remote,  indeed,  as  the  prehistoric 
period  of  the  Cave  Dwellers — that  it  has  been  found  im- 
possible to  determine  with  certainty  its  true  origin.  By 
some  the  parent  stock  is  considered  to  be  the  Ovis  ammon 
of  the  mountains  of  Central  Asia,  where  the  tribes  have 
always  been  pastoral  in  their  habits  and  occupations.  The 
climate,  breed,  food,  and  rearing  of  the  sheep,  all  influence 
the  quality  of  the  wool.  When  they  are  fed  upon  herbage 
grown  in  chalky  districts,  for  example,  the  wool  is  apt  to 
be  coarse,  whereas  it  becomes  fine  and  silky  on  those  reared 
upon  a  rich  loamy  soil. 

Sheep's  wool  varies  from  the  long,  straight,  coarse 
hair  of  certain  varieties  of  the  English  sheep  (Leicester, 
Lincolnshire,  etc.),  to  the  comparatively  short,  wavy,  fine 
soft  wool  of  the  Merino  or  botany. 

Down  to  the  end  of  the  18th  century  the  Spanish 
Merino  sheep  yielded  the  finest  and  best  wool  in  the 
world.  About  that  period  this  variety  was  imported  into 
nearly  every  country  in  Europe,  and  by  careful  selection 
and  good  breeding,  the  wool-growers  of  Saxony  and  Silesia 
at    length    succeeded    in    producing    wool    which  quite 


30 


TEXTILE  FABRICS. 


equalled  that  of  the  original  Spanish  race.  Merino  sheep 
have  since  been  introduced  into  Australia,  the  Cape  of 
Good  Hope,  New  Zealand,  etc.  ;  and  these  so-called 
Colonial  wools,  so  much  used  and  appreciated  at  the 
present  time,  all  bear  the  Merino  character  derived  from 
the  original  Spanish  stock. 

According  to  the  average  length  of  the  fibres  com- 
prising the  locks  of  wool,  or  "  staple,"  two  principal 
classes  of  wool  may  be  distinguished,  namely,  the  long- 
stapled  (18-23  cm.  =  7-9  in.),  and  the  short-stapled  wools 
(2'5-4  cm.  =  1-1'6  in.)  In  the  process  of  manufacture  into 
cloth,  the  former  require  to  be  combed,  and  serve  for  the 


Fig.  7. — Microscopical  Appearance  of  Wool  Fibre. 

production  of  so-called  "  worsted  "  goods,  while  the  latter 
are  carded,  and  used  for  "  woollen  "  goods.  This  dis- 
tinction between  worsted  and  woollen  goods  refers  rather 
to  the  operations  of  combing  and  carding  than  to  the 
length  of  staple  of  the  wool  employed,  since  large  quan- 
tities of  worsted  are  made  from  short  wool.  The  essential 
difference  is  really  owing  to  a  different  arrangement  of 
the  fibres  in  the  yarn.  The  diameter  of  the  wool  fibre 
may  vary  from  0'007-0'5  mm.  =  *002-*02  in. 

Very  marked  differences  exist  even  in  the  wool  of  the 
same  animal,  according  to  the  part  of  the  body  from  which 
it  is  taken,  and  it  is  the  duty  of  the  wool-sorter  to  dis- 
tinguish and  separate  the  several  qualities  in  each  fleece. 

The  Physical  Structure  of  wool  fibre  is  very  character- 
istic, and  enables  it  to  be  readily  distinguished  from  other 
textile  fibres.    Being  a  product  of  the  epidermal  layer  of 


WOOL. 


31 


the  skin,  it  is  built  up  of  an  immense  number  of  epithelial 
cells.  When  carefully  examined  under  the  microscope, 
a  wool  fibre  is  seen  to  consist  of  at  least  two  parts,  some- 
times even  of  three. 

(1)  The  external  cells  appear  as  thin  horny  plates  or 
scales  of  irregular  shape;  they  are  arranged  side  by  side 
and  overlapping  each  other,  somewhat  after  the  manner 
of  roof-tiles  (Fig.  7).  The  upper  edges  are  more  or  less 
free,  the  lower  are  apparently  imbedded  in  the  interior 
of  the  fibre.  In  merino  wool  the  scales  appear  funnel- 
shaped,  and  fit  into  each  other,  each  one  entirely  surround- 
ing the  fibre.  In  hair  they  are  more  deeply  imbedded; 
they  also  lie  flatter,  and  present  but  little  free  margin. 

This  surface-character  plays  an  important  part  in 
causing  the  "  felting  "  of  wool  in  "  milling,"  etc.  During 
this  and  similar  operations,  in  which  a  large  number  of 
fibres  are  brought  into  close  and  promiscuous  contact, 
each  fibre  naturally  moves  more  readily  in  one  direction 
than  in  the  other,  and  the  opposing  scales  gradually  be- 
come interlocked. 

(2)  The  cortical  substance  of  the  wool  fibre  constituting 
nearly,  and  sometimes  entirely,  the  whole  internal  portion 
of  the  fibre,  is  composed  of  narrow  spindle-shaped  cells, 
which  have  assumed  a  more  or  less  horny  character.  This 
structure,  which  gives  the  inner  portion  of  a  wool  fibre 
a  fibrous  appearance  when  examined  longitudinally  under 
the  microscope,  is  best  seen  after  gently  heating  the  fibre 
with  sulphuric  acid.  By  means  of  a  pair  of  dissecting 
needles  it  is  then  readily  separated  into  its  constituent 
cells. 

In  Fig.  8  b  represents  the  microscopic  appearance  of 
the  fibre  after  treatment  with  acid,  and  A  shows  some  of 
the  individual  cells. 

It  is  an  interesting  fact  that  these  disintegrated  inter- 
nal cells  possess  a  greater  attraction  for  colouring  matter 
than  the  external  scales,  and  the  beneficial  effect  of  the 
acidity  of  the  bath,  required  in  many  cases  of  mordanting 
and  dyeing,  may  possibly  be  ascribed  to  the  opening  out  of 
the  epithelial  scales  and  the  exposure  of  the  inner  fibrous 
cells  to  the  action  of  the  liquid  of  the  bath. 

(3)  The  central,  or  medullary,  portion  of  the  wool 
fibre,  when  present,  is  formed  of  several  layers  of  rhombic 


32 


TEXTILE  FABRICS. 


or  cubical  cells,  which  appear  as  the  marrow  or  pith  of 
the  fibre,  and  may  traverse  its  whole  length  or  appear 
only  in  parts.  By  boiling  the  fibre  with  alkali,  it  is  often 
possible  to  squeeze  out  this  medullary  portion.  In  many 
classes  of  wool  (merino,  etc.)  it  seems  to  be  entirely  ab- 
sent :  indeed,  its  presence  or  absence  depends  upon  a 
variety  of  factors,  as  race,  health  of  sheep,  part  of  the 
body  from  which  the  wool  is  taken,  etc. 

In  colourless  wool  the  medullary  portion  often  appears 
under  the  microscope  as  a  dark  or  dull  hazy  stripe.  This 
appearance  is  caused  by  the  air  enclosed  between  the  cells, 


Fig\  8. — Cells  of  Wool  Fibre  under  the  Microscope. 


so  that  by  boiling  such  a  fibre  with  turpentine  or  glycerine 
the  cells  become  transparent. 

Wool  fibres  which  exhibit  the.  medullary  cells  are  brittle 
and  stiff ;  altogether  they  possess  more  of  a  hairy  character, 
and  are  less  suitable  than  other  varieties  for  manufactur- 
ing purposes.  In  the  best  qualities  of  wool  the  medullary 
cells  are  invisible. 

In  a  transverse  section  a  wool  fibre  appears  more  or 
less  round  or  oval. 

Fig.  9  gives  the  cross  sections,  according  to  F.  Bowman, 
of  two  typical  wool  fibres ;  A  shows  the  medullary,  cortical, 
and  external  cells ;  in  B  the  medullary  cells  are  absent. 

"  Kemps,"  or  dead  hairs,  are  certain  wool  fibres  not 
possessing  the  normal  structure  of  good  wool ;  under  the 
microscope  the  epithelial  scales  are  less  distinct,  or  even 


WOOL. 


33 


invisible,  and  viewed  by  transmitted  light,  either  the 
whole  substance  of  the  fibre  seems  more  dense  and  some- 
times even  opaque,  or  the  medullary  portion  only  is 
opaque.  They  are  deficient  in  tenacity,  lustre,  and  felt- 
ing power,  and  in  their  attraction  for  colouring  matters. 
They  may  occur  even  in  good  qualities  of  wool,  about  the 
neck  and  legs  of  the  animals.  In  coarse  wools  they  may 
be  found  in  any  part  of  the  fleece. 

A  merino  wool  fleece  is  made  up  of  an  immense  number 
of  small  bundles  or  strands  of  wool  fibres,  which,  in  the 
best  races  of  sheep,  show  a  perfectly  regular  and  fine  wavy 
character.  The  individual  fibres  are  also  more  or  less 
wavy,  but  not  with  the  same  degree  of  regularity  as  the 
strand  of   which  they   form   a   part.    When   the  fibres 


Fig.  9. — Cross  Section  of  Typical  Wool  Fibres. 


adhere  to  each  other,  as  in  the  strand,  the  regular  wavy 
character  is  very  marked. 

The  hairy  covering  of  animals  other  than  sheep's  wool 
is  used  in  the  woollen  industry. 

Foreign  W ools. — Alpaca,  Vicuna,  and  Llama  wool  are 
obtained  from  different  species  of  the  genus  Auchenia 
(A.  alpaca,  A.  vicugnia,  A.  llama),  which  inhabit  the 
mountains  of  Peru  and  Chile. 

Mohair  is  obtained  from  the  Angora  goat  (Capra  hircus 
angorensis)  of  Asia  Minor. 

Cashmere  consist  of  the  soft  under-wool  of  the  Cash- 
mere goat  (Capra  hircus  laniger)  of  Tibet. 

The  soft  under-wool  of  the  camel,  which  it  sheds  each 
spring,  is  also  used.  Of  all  these,  the  alpaca  and  mohair 
are  most  largely  employed. 

Certain  of  these  foreign  wools,  more  especially  Van 
Mohair,  also  Alpaca,  Camel's  hair,  Cashmere,  and  Persian 
c 


34 


TEXTILE  FABRICS. 


wool,  are  apt  to  be  dangerous  to  the  health  of  the  wool- 
sorter.  They  seem  to  contain  the  microscopic  organism 
known  as  Bacillus  anthracis,  the  same  which  excites  splenic 
fever  in  cattle  and  horses.  When  taken  into  the  bronchial 
tubes  of  man,  it  induces  a  kind  of  blood-poisoning  known 
as  "  wool-sorter's  disease. ;;  Although  once  very  common, 
this  disease  is  now  rare,  for  there  are  stringent  regula- 
tions as  to  the  boards  and  rooms  where  dangerous  wools 
are  sorted. 

Hygroscopicity  of  Wool. — Wool  fibre  is  capable  of  ab- 
sorbing a  large  amount  of  water  without  appearing  damp, 
that  is,  it  is  very  hygroscopic.  Exposed  to  the  air  in 
warm,  dry  weather,  it  contains  8-12  %  moisture ;  but  if 
kept  for  some  time  in  a  damp  atmosphere,  it  may  take 
up  as  much  as  30-50  %.  This  moisture  probably  fills  up 
the  interstices  between  the  cells  of  the  fibre,  which  under 
ordinary  circumstances  contain  air,  but  it  no  doubt  also 
permeates  the  substance  of  the  cells  themselves.  It  is 
noteworthy  that  damp  wool  is  not  so  liable  to  mildew 
as  the  vegetable  fibres  are. 

The  amount  of  moisture  in  unwashed  wool  varies  with 
the  fatty  matter  it  contains,  the  less  fat  the  more  moisture ; 
while  in  washed  wool  it  depends  upon  the  arrangement  of 
the  cells.  The  wool  which  has  least  tenacity — that  is, 
that  in  which  the  cells  are  more  loosely  arranged — pos- 
sesses the  greatest  hygroscopicity. 

This  hygroscopic  character  of  wool  renders  it  very 
desirable  that  those  trading  with  it  should  know  exactly 
its  condition  in  this  respect  at  the  time  of  buying  and 
selling,  hence  conditioning  houses  have  been  established  in 
this  country  and  on  the  Continent,  where  the  exact  amount 
of  moisture  in  any  lot  of  wool  may  be  officially  deter- 
mined. The  legal  amount  of  moisture  allowed  on  tops  in 
the  oil  is  19  %,  on  tops  combed  without  oil  and  worsted 
yarn  18j  %,  and  on  woollen  yarn  17  %. 

If  wool  fibre  is  steeped  in  warm  water,  it  softens 
and  swells  very  considerably,  and,  like  all  horny  sub- 
stances, becomes  plastic,  retaining  any  position  which  may 
be  forced  upon  it,  if,  while  the  mechanical  strain  is  con- 
tinued, the  moisture  is  more  or  less  evaporated  and  the 
temperature  reduced. 

This  hygroscopic  and  plastic  nature  of  wool  comes 


WOOL. 


35 


into  play  in  the  processes  of  "  crabbing  "  and  "  steaming  " 
of  unions,  in  the  "  boiling  "  and  "  finishing  "  ("  hot-press- 
ing ?;)  of  woollen-cloth,  and  in  the  "  stretching     of  yarn. 

Elasticity  of  Wool. — Closely  connected  with  the  hygro- 
scopic nature  of  wool  is  its  elasticity,  which  it  possesses 
in  a  high  degree,  not  merely  because  of  the  wavy  character 
of  the  fibre,  but  also  on  account  of  its  substance  and 
structure.  One  important  manifestation  of  its  elasticity 
is  shown  if  a  dry  wool  fibre  is  excessively  stretched ;  when 
the  ends  are  released,  or  rupture  takes  place,  the  fibre 
or  the  separated  parts  rebound  to  the  original  position, 
and  an  additional  shrinking  and  curling  up  of  the  ends 
are  exhibited. 

If  a  single  wool  fibre  is  softened  by  heat  and  moisture, 
then  stretched  and  dried  in  this  condition,  it  is  found  to 
have  lost  this  curling  property,  but  it  reappears  whenever 
the  stretched  fibre  is  again  softened,  and  allowed  to  dry  in 
an  unfettered  condition. 

In  conjunction  with  pressure,  friction,  and  tempera- 
ture, many  of  the  above-mentioned  physical  features — 
such  as  the  scaly  surface  of  the  fibre,  its  waviness,  and  its 
hygroscopic,  elastic,  and  plastic  nature — play  a  most  im- 
portant part  in  the  processes  of  "  felting  "  and  "  milling  " 
woollen  cloth. 

The  lustre  of  wool  varies  very  considerably.  Straight, 
smooth,  stiff  wool  has  more  lustre  than  the  curly  merino 
wool.  The  differences  exhibited  depend  partly  upon  the 
internal  structure,  but  chiefly  upon  the  varying  arrange- 
ment and  transparency  of  the  scales  on  the  surface  of 
the  fibre;  the  flatter  these  are  and  the  more  they  lie  in 
one  plane,  the  greater  will  be  the  lustre.  Wools  such  as 
Lincoln  and  Leicester,  etc.,  which  possess  a  silky  lustre  in 
a  high  degree,  are  classed  as  lustre  wools,  as  distinguished 
from  non-lustre  wools,  such  as  Merino,  Colonial,  etc. 

Wool  with  a  glassy  lustre,  such  as  bristles,  etc.,  is 
harder  and  more  horny  than  non-lustre  wool;  the  surface 
is  smoother,  the  scales  are  less  distinct,  and  wools  of  this 
kind  do  not  dye  so  readily. 

The  best  kind  of  wool  is  colourless,  but  lower  qualities 
are  often  yellowish,  and  sometimes  variously  coloured, 
such  as  black,  brown,  red,  etc.  This  coloration  is  caused 
by  the  presence  of  an  organic  pigment  in  the  cortical 


36 


TEXTILE  FABRICS. 


portion  of  the  fibre,  either  as  a  granular  pigment  situ- 
ated between  the  cells,  or  as  a  colouring  matter  diffused 
throughout  the  cell  substance.  Generally,  both  forms  are 
present,  but  in  brown  and  black  wool  -the  granular  pig- 
ment predominates,  while  in  red  and  yellow  wools  the 
diffused  colouring  matter  is  more  prominent.  These 
natural  pigments  are  not  so  fast  to  light  as  is  generally 
supposed,  a  fact  which  is  revealed  by  the  bleached  appear- 
ance of  the  exposed  portions  of  the  fleece. 

The  worth  of  any  quality  of  wool  is  determined  by 
carefully  observing  a  number  of  its  physical  properties, 
such  as  softness,  fineness,  length  of  staple,  waviness,  lustre, 
strength,  elasticity,  flexibility,  colour,  and  the  facility 
with  which  it  can  be  dyed.  Fleece  wool,  as  shorn  from  the 
living  animal,  is  superior  in  quality  to  "  dead  wool,'7  that 
is,  wool  which  has  been  removed  from  the  skin  after  death, 
if  lime  has  been  used  in  the  process,  but  if  it  be  removed 
from  the  skins  by  cutting,  the  wool  is  practically  equiva- 
lent to  "  fleece  wool  77 ;  indeed,  it  is  said  to  felt  better  than 
the  latter.  Individual  dead  fibres  occur  occasionally  in 
fleece  wool ;  they  have  been  forced  out  by  the  roots  previous 
to  the  time  of  shearing,  and  constitute  the  so-called  "  over- 
grown 77  wool.  This  wool  is  comparatively  harsh  and 
weak,  and  does  not  dye  so  readily  as  other  kinds.  This 
is  the  case  also  with  the  wool  of  an  animal  which  has  died 
of  some  distemper. 

Chemical  Composition  of  Wool. — A  distinction  must  be 
made  between  the  fibre  proper  and  the  foreign  matters 
encrusting  it.  The  latter,  though  consisting  partly  of 
mechanically  adhering  impurities  derived  from  without, 
are  mainly  secreted  by  the  animal,  and  constitute  the 
so-called  Yolk  (Fr.  Suint).  It  may  be  remarked  that  it 
is  the  estimation  of  these  foreign  matters  which  makes 
wool-buying  so  difficult  and  necessitates  both  experience 
and  quick  judgment  to  prevent  later  loss. 

Wool  fibre  which  has  been  entirely  cleansed. and  freed 
from  these  foreign  matters  possesses  a  chemical  composi- 
tion very  similar  to  that  of  horn  and  feathers,  and  consists 
of  what  is  termed  Keratin  (horn-substance).  Its  ele- 
mentary composition  varies  somewhat  in  different  qualities 
of  wool,  but  the  following  analysis  of  German  wool  may 
be  taken  as  representative  :-— 


WOOL. 


37 


Carbon 
Hydrogen 
Oxygen  . 
Nitrogen  .. 
Sulphur  . 


49-25% 
7*57% 
23-66 
15-86 
366 

100-00 


Whether  the  sulphur  is  an  essential  constituent  or  not 
is  a  question  that  has  been  much  discussed.  It  is  re- 
moved to  a  greater  or  less  degree  by  most  solvents,  hence 
it  is  difficult  to  obtain  constant  analytical  results.  Its 
amount  has  been  found  to  vary  in  different  wools  from 
0'8-3"8  %.  Its  constant  occurrence,  and  that  in  compara- 
tively large  proportion,  precludes  the  idea  that  it  is 
merely  an  accidental  constitutent,  and  it  has  hitherto 
been  found  impossible  to  deprive  wool  entirely  of  its 
sulphur,  without,  at  the  same  time,  modifying  somewhat  its 
structure  and  in  large  measure  destroying  its  tenacity. 

This  presence  of  sulphur  in  wool  is  attended  with  some 
practical  disadvantages.  The  wool  is  apt  to  contract  dark- 
coloured  stains  under  certain  conditions,  and  on  that 
account  its  contact  with  such  metallic  surfaces  as  those 
of  lead,  copper,  and  tin  should  be  avoided  during  processes 
of  scouring  or  dyeing.  In  mordanting  with  stannous 
chloride  and  cream  of  tartar,  especially  if  an  excess  of 
these  ingredients  be  used,  the  wool  is  frequently  stained, 
by  reason  of  the  formation  of  stannous  sulphide. 

A  boiling  solution  of  plumbite  of  soda  at  once  blackens 
wool,  and  may  thus  serve  to  distinguish  it  from  silk  or 
cotton. 

For  practical  purposes,  much  of  the  sulphur  may  be  re- 
moved by  steeping  the  wool  in  cold  weak  alkaline  solutions, 
such  as  milk  of  lime — then  washing  it  in  water,  in  weak 
hydrochloric  acid,  and  again  with  water,  repeating  the 
operations  several  times. 

The  amount  of  mineral  matter  in  wool  free  from  yolk 
varies  from  0*08-0'37  %.  It  consists  mainly  of  phosphates 
and  silicates  of  lime,  potash,  iron,  and  magnesia. 

Action  of  Heat  on  Wool. — Heated  to  130°  C,  wool  be- 
gins to  decompose  and  give  off  ammonia;  at  140-150°  C. 
vapour  containing  sulphur  is  disengaged. 

Wool  fibre  inserted  in  flame  burns  with  some  difficulty, 
and  emits  a  disagreeable  odour  of  burnt  feathers.    It  has 


38 


TEXTILE  FABRIC 8. 


the  appearance  of  fusing,  a  bead  of  porous  carbon  being 
formed  at  the  end  of  the  fibre.  Submitted  to  dry  dis- 
tillation, it  gives  off  products  containing  much  ammonium 
carbonate,  which  may  be  readily  detected  by  its  smell  or 
by  its  colouring  red  litmus-paper  blue.  These  reactions 
serve  to  distinguish  wool  from  all  vegetable  fibres. 

A  cold  ammoniacal  solution  of  cupric  hydrate  has  no 
action  upon  wool,  but  if  it  is  used  hot  the  wool  is  dis- 
solved. 

Action  of  Acids  on  Wool. — Dilute  solutions  of  hydro- 
chloric and  sulphuric  acids,  whether  applied  hot  or  cold, 
have  little  influence  upon  wool,  further  than  opening  out 
the  scales  and  making  the  fibre  feel  somewhat  rougher, 
but  if  used  concentrated,  the  fibre  is  soon  disintegrated ; 
in  any  case  their  destructive  action  is  by  no  means  so 
energetic  on  wool  as  on  cotton.  This  fact  is  made  use  of 
to  separate  cotton  from  wool  in  the  process  of  "  extract- 
ing 7 ;  or  "  carbonising  ;;  rags  containing  both  fibres.  The 
rags  are  steeped  in  dilute  sulphuric  acid,  and  after  re- 
moving the  excess  of  liquid,  are  dried  in  a  stove  at  about 
110°  C.  The  disorganised  cotton  can  then  be  beaten  out 
as  dust,  while  the  wool  remains  comparatively  little  in- 
jured. Another  method  is  to  submit  the  rags  for  a  few 
hours  to  heated  hydrochloric  acid  gas.  The  above  mineral 
acids  are  frequently  added  to  the  dye-bath  in  wool-dyeing. 

Nitric  acid  acts  like  the  acids  just  mentioned,  but  it 
also  gives  a  yellow  colour  to  the  wool,  owing  to  the  pro- 
duction of  so-called  xanthoproteic  acid.  Because  of  the 
comparatively  light  yellowish  colour  thus  imparted,  boil- 
ing dilute  nitric  acid  is  frequently  used  as  a  "  stripping  " 
agent  for  wool — to  destroy  the  colour  in  wool  already 
dyed — for  the  purpose  of  re-dyeing  (job-dyeing,  rectifying 
mistakes,  etc.).  Care  must  always  be  taken  not  to  have 
the  acid  too  strong  (about  3°-4°  Tw.— Sp.  Gr.  1*02),  and 
not  to  prolong  the  process  beyond  three  or  four  minutes. 

Sulphur  dioxide  (sulphurous  acid  gas)  removes  the 
natural  yellow  tint  from  ordinary  wool,  and  is  the  best 
bleaching  agent  employed  for  this  fibre.  It  is  important 
to  remember  that  the  gas  is  very  persistently  retained  by 
the  fibre,  and  should  always  be  removed  from  bleached 
wool  previous  to  dyeing  light  colours.  This  is  effected 
by  steeping  the  wool  in  very  dilute  solutions  of  carbonate 


WOOL. 


39 


of  soda  or  bleaching-powder,  and  washing  well.  When 
the  first  reagent  is  employed,  the  acid  is  merely  neutral- 
ised, but  with  the  second  the  sulphurous  acid  is  oxidised 
to  sulphuric  acid.  Should  this  precaution  be  neglected, 
the  wool  will  not  dye  properly,  or,  when  dyed,  it  will  be 
liable  to  become  decolorised  again  through  the  reducing 
action  of  the  sulphur  dioxide  retained  by  the  fibre. 

Action  of  Alkalis  on  Wool. — Alkaline  solutions  have  a 
very  sensible  influence  on  wool,  but  the  effects  differ  con- 
siderably according  to  the  nature  of  the  alkali,  the  con- 
centration and  temperature  of  the  solution,  and  the 
duration  of  contact. 

Caustic  alkalis,  (KHO,  NaHO)  act  injuriously  on  wool 
under  all  circumstances.  Even  when  they  are  applied 
as  cold  and  weak  solutions,  their  destructive  action  is 
sufficient  to  warrant  their  complete  rejection  as  "  scour- 
ing "  agents. 

When  they  are  applied  hot,  even  though  but  little  con- 
centrated, the  wool  is  gradually  dissolved,  producing  a 
soapy  liquid  from  which  it  may  be  precipitated,  on  the 
addition  of  acid,  as  a  white  amorphous  mass. 

This  fact  of  the  solubility  of  wool  in  hot  caustic  alkalis 
is  utilised  for  the  purpose  of  recovering  indigo  from 
vat-dyed  woollen  rags,  this  colouring  matter  being  in- 
soluble therein. 

Solutions  of  alkaline  carbonates  and  of  soap  have  little 
or  no  injurious  action  on  wool,  if  they  are  not  too  con- 
centrated, and  the  temperature  is  not  higher  than  50°  C. 
Soap  and  carbonate  of  ammonia  have  the  least  injurious 
action,  while  the  carbonates  of  potash  and  soda  impart  to 
the  wool  a  yellow  tint,  and  leave  it  with  a  slightly  harsher 
and  less  elastic  feel. 

This  marked  difference  of  action  between  the  caustic 
and  carbonated  alkalis  makes  it  an  all-important  matter 
for  every  wool-scourer  to  know  the  exact  nature  of  the 
agents  he  uses  :  soaps  should  be  free  from  excess  of  alkali, 
"  soda  ash  ;?  should  contain  no  caustic  soda,  etc. 

Calcium  hydrate  (lime)  acts  injuriously,  like  the 
caustic  alkalis,  but  in  a  less  degree.  It  eliminates  the  sul- 
phur from  the  wool,  but  thereby  renders  the  fibre  brittle 
and  impairs  its  milling  properties. 

Action  of  Chlorine  and  Hypochlorites  on  Wool. — These 


40 


TEXTILE  FABRICS. 


act  injuriously,  and  can  therefore  never  be  applied  as 
bleaching  agents.  A  hot  or  boiling  solution  of  chloride  of 
lime  entirely  destroys  the  fibre,  with  evolution  of  nitrogen 
gas ;  if,  however,  wool  be  submitted  to  a  very  slight  action 
of  chlorine  or  hypochlorous  acid,  it  assumes  a  yellowish 
tint,  and  acquires  at  the  same  time  an  increased  affinity 
for  many  colouring  matters.  This  effect  is  possibly  due 
to  an  oxidation  of  the  fibre,  and  not  merely  to  a  roughen- 
ing of  its  surface.  Practical  use  is  made  of  it  by  the 
printer  of  Muslin  Delaine  (mixed  fabrics  of  cotton  and 
wool)  and  occasionally  by  the  woollen  dyer. 

Action  of  Metallic  Salts  on  Wool. — In  common  with  all 
fibres  of  animal  origin,  wool  has  the  property  of  readily 
dissociating  certain  metallic  salts  when  in  contact  with 
their  solutions,  especially  if  the  latter  are  heated.  When, 
for  example,  wool  is  boiled  with  solutions  of  the  sulphates, 
chlorides,  or  nitrates  of  aluminium,  tin,  copper,  iron, 
chromium,  etc.,  a  small  amount  of  the  oxides  or  of  in- 
soluble basic  salts  of  these  metals  is  deposited  upon  or 
attracted  by  the  fibre,  and  a  more  acid  salt  remains  in 
solution.  On  this  fact  depends  the  method  of  mordanting 
wool,  which  differs  from  that  employed  with  the  vegetable 
fibres,  since  these  do  not  cause  dissociation  under  like 
conditions.  Neutral  salts  of  the  alkalis  (such  as  NaCl, 
Na2S04)  exercise  no  appreciable  action  on  wool. 

Action  of  Colouring  Matters  on  Wool. — Wool  has  a 
marked  direct  attraction  for  certain  colouring  matters 
(magenta,  azo-scarlet,  indigo  extract,  orchil,  etc.)  if  their 
solutions  are  presented  to  it  in  a  proper  state  of  neutrality 
or  acidity,  etc.,  and  with  these  it  is  dyed  with  great 
facility.  Being  of  a  porous  nature,  it  is  indeed  readily 
permeated  by  solutions  of  all  colouring  matters,  especi- 
ally when  heated  with  the  latter. 

Yolk  in  Raw  Wool.— The  foreign  matter,  or  yolk,  en- 
veloping the  pure  wool  fibre  possesses  a  special  interest 
for  the  dyer,  because  on  its  entire  removal  depends  to  a 
very  large  extent  the  success  with  which  he  may  obtain 
fast,  pure,  and  even  colours.  To  the  merchant  and  manu- 
facturer it  is  also  of  great  importance,  since  the  amount 
in  different  kinds  of  raw  wool  varies  considerably,  and 
influences  its  commercial  value. 

J*y  treating  wool  first  with  distilled  water,  and  after- 


WOOL. 


wards  with  alcohol,  Chevreul  obtained  the  following  analy- 
sis of  raw  merino  wool  dried  at  100°  C.  :  — 


liemoved  j  Yolk  soluble  in  cold  distilled  water   32\T4# 

by  water,  j  Earthy  matter  deposited  from  the  above    26*06% 

Removed  (  Fatty  matter  dissolved  by  alcohol    8-57% 

by       <  Earthy  matter  adhering  to  the  fat    ...        ...        ...  1*40% 

alcohol    (Wool  fibre    31  '23% 


100-00 

Chevreul  has  here  designated  as  yolk  only  those  im- 
purities which  are  soluble  in  cold  water,  although  in  the 
ordinary  commercial  acceptation  of  the  term  it  includes 
all  adhering  impurities. 

According  to  other  observers,  the  amount  of  the  main 
constituents  of  "  raw  ;'  or  "  greasy  ;;  wool,  just  as  it 
comes  from  the  sheep's  back,  may  vary  considerably,  ac- 
cording to  its  origin,  as  follows  : — 

Moisture  ...       .:   4-24% 

Yolk    12-47% 

Wool  fibre    15-72% 

Dirt      3-24% 

As  a  rule,  the  finer  qualities  of  wool,  such  as  merino, 
contain  more  yolk  than  the  coarser. 

When  wool  is  washed  with  water,  as  in  ChevreuPs  an- 
alysis, not  only  are  certain  constituents  of  a  soapy  nature 
— i.e.  alkaline  oLeates — removed,  but  some  of  the  un- 
saponifiable  matter  as  well,  since  the  oleates  cause  it  to 
form  an  emulsion. 

A  better  method  of  separating  these  two  constituents  is 
to  treat  the  dried  raw  wool  first  with  ether.  This  dis- 
solves principally  the  fatty  matter,  and  although  it  also 
takes  up  as  much  as  10  %  of  the  oleates  present,  repeated 
washing  of  the  ethereal  solution  with  water  removes  the 
latter  almost  entirely. 

The  following  substances  may  thus  be  distinguished  in 
raw  wool — wool-fat  (soluble  in  ether),  wool-perspiration 
(soluble  in  water,  and  partly  also  in  alcohol),  wool  fibre, 
dirt,  moisture. 

These  may  be  determined  as  follows  : — 

(a)  Weigh  the  raw  wool,  dry  it  at  100°  C,  preferably  in 
a  stream  of  some  dried  inert  gas — as  hydrogen — and  weigh 
again.    The  loss  in  weight  gives  the  moisture  present. 


42 


TEXTILE  FABRICS. 


(b)  Extract  the  dried  wool  with  ether,  shake  up  the 
ethereal  solution  with  water,  in  order  to  remove  from  it 
the  oleates;  evaporate  the  separated  ether  to  dryness,  and 
weigh  the  fatty  residue.  The  weight  gives  the  amount 
of  wool-fat  present.  Evaporate  the  separated  wash-water 
to  dryness,  weigh  the  residue,  and  add  the  weight  to  that 
of  the  portion  soluble  in  water  :  the  oleates. 

(c)  Wash  the  ether-extracted  wool  several  times  with 
cold  distilled  water,  and  evaporate  the  solution  to  dryness. 
The  weight  of  the  residue  added  to  the  weight  of  the 
oleates  dissolved  by  water  from  the  ethereal  solution 
gives  the  chief  amount  of  the  alkaline  oleates  present. 
The  wool  is  then  washed  with  alcohol ;  this  always  dis- 
solves further  minute  quantities  of  oleates,  the  weight 
of  which  must  be  added  to  the  above.  Earthy  oleates 
which  remain  in  the  wool  are  decomposed  by  washing 
the  latter  with  dilute  hydrochloric  acid ;  the  acid  is  re- 
moved by  washing  with  water,  the  wool  is  then  dried, 
and  extracted  with  ether  and  alcohol.  From  the  weight 
of  the  residue  obtained  on  evaporating  the  two  last  sol- 
vents to  dryness  the  amount  of  earthy  oleates  present  in 
the  wool  may  be  calculated.  With  very  dirty  wool  a  good 
deal  of  lime  is  dissolved  by  the  hydrochloric  acid,  not 
because  of  lime  soaps  but  of  calcareous  dust  present. 

(d)  The  wool  remaining  is  dried  and  thoroughly  well 
shaken  and  teazed  out  by  hand  over  a  large  sheet  of 
paper,  in  order  to  remove  dirt,  sand,  etc.  ;  care  is  taken 
not  to  lose  any  of  the  fibre,  the  detached  particles  of 
which  are  collected  on  a  fine  sieve,  and  washed  with  water 
till  free  from  dirt.  The  wool  is  dried  and  weighed;  the 
sand,  dirt,  etc.,  are  determined  by  difference. 

The  following  analyses  of  raw  wools  give  the  results 
obtained  by  the  above  method  of  Marcker  and  Schulz  : — 


Moisture  (per  cent.) 
0        Wool- fat  .. 

.5  43  (  Soluble  in  water  (wool-perspira- 

§  S  I  tion)  

§  S  -{  Soluble  in  alcohol 

£  g  |  Soluble  in  dilute  HC1  

£vfi  ^Soluble  in  ether  and  alcohol  ... 
"        Pure  wool  fibre  ... 

Dirt   


Lowland 

Rambouillet 

Pitchy 

Sheep. 

Sheep 

Wool. 

23-48 

12-28 

13-28 

717 

14-66 

34-19 

21-13 

21-83 

9-76 

0-35 

0-55 

0-89 

1-45 

564 

1-39 

0-29 

0*57 

43-20 

20-83 

32-11 

293 

23-64 

8-38 

WOOL. 


43 


Wool-fat. — The  composition  of  what  is  here  called 
wool-fat  is  found  to  be  of  a  somewhat  complicated  nature. 
By  treating  it  with  boiling  alcohol  it  may  be  separated 
into  two  portions,  the  one  soluble,  the  other  and  larger 
amount  insoluble  in  this  liquid.  Further  analysis  has 
shown  that  the  soluble  portion  consists  mainly  of  the 
alcoholic  and  fat-like  body  cholesterine,  together  with 
isocholesterine,  each  in  the  free  state,  and  probably  also 
of  compounds  of  both  these  bodies  with  such  organic  acids 
as  acetic  acid.  The  insoluble  portion  consists  essentially 
of  compounds  of  cholesterine  and  isocholesterine  with  oleic 
acid,  and  in  less  amount  with  solid  fatty  acids,  such  as 
stearic  acid  and  hyaena  acid. 

There  seems  also  to  be  present  in  a  similar  state  of 
combination,  but  in  smaller  quantity,  some  other  amor- 
phous body  or  mixture  of  bodies,  readily  fusible,  of  an 
alcoholic  nature,  and  containing  less  carbon  than  choles- 
terine. A  portion  of  these  various  alcoholic  bodies,  and 
sometimes  also  a  part  of  the  high  atomic  fatty  acids,  are 
present  in  the  free  state. 

Wool-fat  is  certainly  not  a  compound  of  glycerine,  and 
hence  is  not  a  fat  as  ordinarily  understood.  This  ac- 
counts for  the  difficulty  experienced  in  removing  it  by 
mild  scouring  agents  from  so-called  "  pitchy  wool,"  which, 
as  shown  in  the  above  analysis,  contains  it  in  excessive 
quantity. 

Wool-perspiration. — With  reference  to  the  chemical 
composition  of  that  portion  of  the  yolk  which  is  soluble 
in  water,  the  wool-perspiration,  it  has  been  shown  by  the 
experiments  of  Vauquelin,  Chevreul,  Hartmann,  and 
others,  that  it  consists  essentially  of  the  potassium  com- 
pounds of  oleic  and  stearic  acids,  and  probably  also  of 
other  fixed  fatty  acids ;  it  contains  further,  but  in  smaller 
amount,  the  potassium  salts  of  certain  volatile  fatty  acids 
(acetic  and  valerianic  acid),  potassium  chloride,  phos- 
phates, sulphates,  etc. 

Ammonium  salts  seem  to  be  present  in  dried  extracted 
yolk  in  small  quantity  (equivalent  to  0'5  %  NH3),  not 
sufficient,  however,  to  account  for  the  amount  of  nitrogen 
found  in  yolk  (3  %) ;  some  other  nitrogenous  body  is 
evidently  present. 

As  a  rule,  the  wash-water  of  raw  wool  has  a  strong 


44 


TEXTILE  FABRICS. 


alkaline  reaction,  since  potassium  carbonate  may  be  pre- 
sent to  the  amount  of  4  %  of  the  weight  of  raw  wool. 
Some  observers  have  found  it  to  be  entirely  absent,  in 
which  case,  however,  it  may  still  be  considered  to  have 
been  secreted  by  the  perspiration  glands  of  the  sheep,  but 
to  have  afterwards  acted  energetically  upon  the  wool-fat 
and  saponified  it,  so  that  while  disappearing  itself,  it  has 
given  rise  to  an  increased  amount  of  potash-soaps  in  the 
wool-perspiration. 

In  washing  wool  on  the  sheep's  back,  this  potassium 
carbonate,  when  present,  plays  a  not  unimportant  part 
along  with  the  potash  soaps  of  the  yolk,  in  greatly  facili- 
tating the  removal  of  dirt,  etc.,  from  the  fleece. 

Dried  extracted  yolk  contains  about  60  %  organic 
matter  and  40  %  mineral  matter  (free  from  C02). 

The  following  are  two  analyses  of  yolk-ash  by  Marcker 
and  Schulz  : — 


Potash 

  58 -94% 

63-452 

Soda  ... 

  2-762 

trace 

Lime  ... 

  2'U% 

2-192 

Magnesia 

  1-072 

0-852 

Ferric  oxide  ... 

trace 

trace 

Chlorine 

  4-26% 

3-832 

Sulphuric  acid 

  3-13^ 

3-202 

Phosphoric  acid 

  0-732 

0-702 

Silicic  acid  ... 

  1  392 

1-072 

Carbonic  acid 

  25-792 

25-342 

Yolk-ash  consists  essentially,  therefore,  of  potash  salts, 
principally  carbonates,  the  carbonic  acid  arising  mainly 
from  the  burning  of  the  organic  constituents  of  the  yolk. 

Maumene  and  Rogelet  give  the  following  analysis, 
which  closely  agrees  with  the  above  : — 


Potassium  carbonate      ...       ...        ...        ...  86  782 

Potassium  chloride       ...        ...       ...        ...  6-182 

Potassium  sulphate       ...       ...        ...        ...  2-832 

Si02,  P205,  CaO,  MgO,  AL>03, 

Fe203,  Mn203,  CuO      .    4-212 


100-002 

It  is  evident  from  the  above  that  when  wool  is  washed 
on  the  sheep's  back  a  considerable  quantity  of  potash  is 
entirely  lost  to  the  farmer.  It  has  been  estimated  that 
raw  wool  yields  8*75  %  by  weight  (free  from  C02),  and  if 


WOOL. 


45 


the  nitrogenous  matter  and  phosphates  also  washed  away 
are  taken  into  account,  it  will  be  seen  that  the  wash-water 
of  raw  wool  posesses  an  appreciable  manurial  value. 

The  Wash-Water  Products  of  Raw  Wool—  The  great 
bulk  of  the  commercial  wool  is  in  the  unwashed  or 
"  greasy  ;'  condition,  so  that  an  opportunity  is  afforded 
to  the  woollen  manufacturer  of  extracting  the  whole  of 
the  yolk,  and  making  it  serve  as  a  supplementary  source 
of  potash. 

It  is  interesting  to  know  that  since  1860,  and  based 
mainly  upon  the  observations  of  Maumene  and  Rogelet, 
the  manufacture  of  potash  salts  from  the  wash-water  of 
raw  wool,  used  in  the  centres  of  the  French  and  Belgian 
woollen  industry,  has  become  an  accomplished  fact,  the 
annual  production  of  potassium  carbonate  being  estimated 
at  about  1,000,000  kg. 

After  systematically  washing  the  wool  with  water,  the 
saturated  solution  is  evaporated  to  dryness.  The  residue 
is  heated  in  gas  retorts,  and  the  gas  evolved  may  be  used 
for  illuminating  purposes.  The  resulting  coke  is  either 
calcined  with  access  of  air  or  lixiviated  with  water,  and 
yields  crude  potassium  carbonate.  "  Greasy  ,?  wool  yields 
7-9  %  crude  potassium  carbonate,  containing  85  %  K2C03. 

Another  mode  of  utilising  yolk  is  that  recommended 
by  Havrez,  according  to  whom  it  is  the  natural  raw 
material  for  the  manufacture  of  yellow  prussiate  of 
potash.  The  ordinary  method  of  making  this  salt  is  to 
heat  a  mixture  of  crude  carbonate  of  potash,  waste  animal 
matter  (dried  blood,  leather  clippings,  etc.),  and  iron 
filings.  The  resulting  fused  matter  is  extracted  with 
water,  and  on  evaporating  the  solution  the  desired  salt 
is  obtained. 

Havrez  says  that  when  yolk  is  submitted  to  dry  dis- 
tillation it  yields  a  residue,  which  is  an  extremely  inti- 
mate mixture  of  carbonate  of  potash  and  nitrogenous 
carbon.  This  residual  coke  contains,  therefore,  just  the 
necessary  elements  for  the  production  of  yellow  prussiate 
of  potash,  and  experiment  has  shown  that  it  gives  even 
a  greater  yield  than  the  ordinary  mixture,  containing  an 
equal  amount  of  K2C03,  because  of  the  perfect  and  inti- 
mate mixture  of  the  various  ingredients. 

Havrez  has  calculated  that  the  money  value  of  the 


46 


TEXTILE  FABRICS. 


yolk,  when  used  for  the  production  of  yellow  prussiate  of 
potash,  is  more  than  twice  that  of  its  ordinary  commercial 
value.  He  further  maintains  that  when  it  is  used  for 
the  simultaneous  production  of  carbonate  of  potash  and 
yellow  prussiate  of  potash,  instead  of  the  former  only, 
there  is  a  gain  in  value  of  50  %.  For  this  purpose  the 
dried  yolk  is  mixed  with  an  equal  weight  of  waste  animal 
matter,  and  heated  somewhat  longer  than  usual.  Experi- 
ment showed  that  carbonate  of  potash  obtained  from 
100  kg.  of  the  residual  melt  was  accompanied  by  17*3  kg. 
of  potassium  cyanide,  which  was  capable  of  yielding  19  kg. 
of  yellow  prussiate  of  potash.  One  hundred  kg.  of  yolk 
treated  in  this  manner  are  said  to  yield  32  kg.  of  carbonate 
of  potash  and  4'3  kg.  of  yellow  prussiate  of  potash. 

Previous  to  its  employment  in  manufacturing  or  in 
dyeing,  the  raw  wool  must  be  thoroughly  cleansed  from 
the  yolk,  but  since  only  a  portion  is  removed  by  a  simple 
treatment  with  water,  recourse  is  had  to  the  detergent 
action  of  solutions  of  soap,  alkaline  carbonates,  etc. 

No  attempt  seems  yet  to  have  been  made  in  England 
to  collect  separately  the  soluble  portion  of  the  yolk  for 
the  purpose  of  recovering  the  potash  salts.  The  pre- 
liminary extraction  with  water,  or  steeping,  alluded  to,  is 
dispensed  with  by  the  manufacturer,  and  the  wool  is  at 
once  washed  with  solutions  mentioned  above.  This  opera- 
tion is  termed  "  scouring/'  and  will  be  treated  of  in 
detail  in  a  future  chapter ;  but  it  may  be  well  to  state 
here  that,  although  in  the  English  method  the  potash 
salts  are  entirely  lost,  the  alkaline  and  detergent  pro- 
perties of  the  soluble  portion  of  the  yolk  are  utilised. 


17 


CHAPTER  IV. 

SILK. 

Origin  and  Culture  of  $ilk.— Silk  differs  entirely  both 
from  the  vegetable  fibres  and  from  wool  by  being  devoid 
of  cellular  structure.  It  consists  of  the  pale  yellow,  bufl> 
coloured,  or  white  fibre,  which  the  silkworm  spins  round 
about  itself  when  entering  the  pupa  or  chrysalis  state. 
The  numerous  varieties  of  silk  may  be  conveniently 
divided  into  two  classes,  cultivated  and  wild  silk.  The 
latter  is  the  product  of  the  larvae  of  several  species  of 
wild  moths,  which  are  natives  of  India,  China,  and  Japan. 
The  former  and  more  important  class  is  produced  by  the 
common  silkworm,  or  caterpillar  of  the  moth  Bombyx 
mori,  which  has  become  the  subject  of  special  culture  (see 
Fig.  12).  The  chief  seats  of  the  silkworm  culture  are 
Southern  Europe  (including  the  South  of  France,  Italy, 
and  Turkey),  Japan,  China,  and  India. 

The  eggs  of  the  European  silk  moth  are  about  the  size 
and  shape  of  poppy  seeds.  One  g.  weight  of  them  contains 
about  1,350  eggs.  They  have  at  first  a  yellowish  colour, 
which,  however,  on  drying,  changes  to  grey.  The  rearing 
of  the  silkworm  is  mainly  conducted  in  specially-arranged 
establishments,  called  Magnameries.  In  these,  the  incuba- 
tion-chamber is  a  well-lighted,  airy  room,  where  the  eggs 
are  spread  out  on  sheets  of  paper  resting  on  lattice-work. 
A  certain  suitable  degree  of  moisture  is  maintained,  and 
the  temperature  is  gradually  raised  in  the  course  of  about 
10-12  days  from  18°-25°  C.  The  young  caterpillars,  as  soon 
as  they  appear,  are  taken  to  a  more  roomy  chamber,  in 
which  there  is  erected  a  lath  framework  strung  across 
with  threads  and  sheets  of  paper.  Here  the  animals  are 
regularly  fed  during  30-33  days,  till,  indeed,  they  begin  to 
spin.  Their  food  consists  of  the  leaves  of  the  mulberry 
tree,  Morns  alba,  hence  the  silk  is  frequently  termed 
mulberry  silk.    During  the  feeding  period  the  silkworm 


48 


TEXTILE  FABRICS. 


increases  enormously  in  size,  to  about  8-10  cm.  (3-4  in.  long) 
and  about  5  g.  (77  grains)  in  weight.  As  might  be  expected, 
such  a  rapid  and  enormous  development  necessitates  a 
frequent  renewal  of  the  skin,  and  moulting  takes  place 
three  or  four  times,  at  tolerably  regular  intervals  of  4-6 
days.  On  or  about  the  thirteenth  day  the  animal  ceases 
to  take  food,  and  evinces  a  restless  activity.  At  this 
period  it  is  placed  on  birch  twigs,  etc.,  where  it  soon 
begins  to  spin.    The  silk  substance  is  secreted  by  two 


glands  symmetrically  situated  on  each  side  of  the  body  of 
the  caterpillar,  below  the  intestinal  canal.  Each  gland, 
as  shown  in  Fig.  10,  consists  of  three  parts  :  a  narrow  tube 
(i  c)  with  numerous  convolutions,  the  veritable  secreting 
portion ;  a  central  part  (c  b)  somewhat  expanded,  and  con- 
stituting the  reservoir  of  the  silk  substance ;  a  capillary 
tube  (b  a),  connecting  the  reservoir  with  a  similar  capillary 
canal  at  A,  common  to  both  glands,  and  situated  in  the 
head  of  the  animal,  whence  issues  the  silk. 

The  silk  substance  as  contained  in  the  central  reservoir 


SILK. 


49 


is  a  clear,  colourless,  gelatinous  liquid.  According  to 
Duseigneur,  this  is  surrounded  by  a  layer  of  another  sub- 
stance, colourless  when  the  silk  is  white,  coloured  when  it 
is  yellow,  and  which  possibly  constitutes  the  silk-gum  to  be 
alluded  to  subsequently.  The  whole  is  enclosed  in  a  thin 
membrane.  A  transverse  section  (Fig.  11)  shows  that  it 
occupies  a  space  equal  to  20-25  %  of  the  total  volume,  a 


Fig.  11.— Section  of  Silk-bag-. 


proportion  which  corresponds  somewhat  to  the  loss  sus- 
tained by  raw  silk  during  the  operation  of  "  boiling-off." 

Arrived  in  the  capillary  tube  at  A  (Fig.  10),  the  silk 
substance  solidifies,  and  issues  from  the  spinneret  in  the 
form  of  a  double  fibre,  as  represented  in  Fig.  12.  Occa- 
sionally  the  two   fibres   may  be   slightly   separated  at 


Fig-.  12. —Microscopic  Appearance  of  Kaw  Silk  Fibre. 

intervals,  and  form  then  at  these  points  two  transparent 
solid  cylinders. 

In  the  beginning  of  its  spinning  operations  the  silk- 
worm throws  round  about  itself  a  light  scaffolding,  as  it 
were,  of  short  fibres  connecting  the  neighbouring  points  of 
support.  When  this  is  completed  its  movements  become 
slower,  and  by  moving  its  head  from  side  to  side  it  gradu- 
ally forms  and  lines  its  dwelling  with  numerous  layers  of 
what  may  be  termed  silken  lattice-work. 
.  D 


50 


TEXTILE  FABRICS. 


Towards  the  interior  of  the  layers  they  become  firmer 
and  denser,  while  the  innermost  one,  which  immediately 
protects  the  animal,  forms  a  thin  parchment-like  skin. 
The  egg-shaped  product  is  called  a  cocoon  (Fig.  13).  It  is 
made  up  of  a  double  fibre,  only  rarely  broken,  varying 
in  length  from  350-1,250  m.  (400-to  1,400  yds.),  and  with  a 
diameter  of  about  0*018  mm.  (0*0007  in.).  Each  fibre  is 
thickest  in  the  outermost  portion  of  the  cocoon,  and  be- 
comes thinner  towards  the  interior,  owing  to  the  exhaus- 
tion of  the  caterpillar  from  want  of  food  during  the  spin- 
ning process. 

The  cocoons  are  white  or  yellow,  contracted  in  the  cen- 
tre, about  3  cm.  =  1*18  in.  long,  and  l'5-2  cm.  =  0*59-0*78 
in.  thick. 

As  soon  as  the  metamorphosis  of  the  caterpillar  into 


the  chrysalis  state  is  completed,  the  cocoons  are  collected. 
Those  which  are  intended  for  breeding  purposes  are  left 
to  themselves  in  a  room  heated  to  19°-20°  C.  Three  weeks 
after  the  spinning  of  the  cocoon,  the  silk  moth,  which  has 
now  been  formed  in  the  interior,  emits  a  peculiar  kind  of 
saliva ;  with  this  the  animal  softens  one  end  of  the  cocoon, 
and  pushes  its  way  out.  A  few  days  after  the  females  have 
laid  their  eggs  they  die,  not  being  provided  with  any 
organ  of  nutrition.  The  eggs  are  slowly  dried,  and  stored 
in  glass  bottles  in  a  dry  dark  place  till  the  following 
spring. 

Experience  has  shown  that  the  worms  issuing  from 
100  g.  of  eggs  consume  3,500-5,000  kg.  *=  3J-5  tons  of  leaves, 
and  produce,  under  favourable  conditions,  87,900-117,200 
cocoons,  weighing  150-200  kg.  =  330*7-440'9  lb.,  and  these 
yield  12-16  kg.  =  26-5-25*3  lb.  of  reeled  silk. 


Fig.  13.— Silk  Cocoon. 


SILK. 


51 


In  their  natural  state  cocoons  contain  generally  : — 

Moisture    &%% 

Silk     WU 

Floss  {bourrc)        ...        ...        ...    0*7% 

Chrysalis  

The  good  silk  is  obtained  from  those  cocoons  of  which 
the  pupae  are  killed,  either  by  heating  the  cocoons  for  2-3 
hours  in  an  oven  heated  to  60°-70°  C,  or  by  means  of 
steam.  The  latter  method  is  the  more  general,  the  ap- 
paratus consisting  essentially  of  a  boiler  for  generating 
the  steam,  and  a  steam-box  in  which  the  cocoons  are  placed. 
When  subjected  to  steam,  the  pupae  are  killed  in  10-12 
minutes. 

The  external  loose  flossy  silk  is  first  removed,  and  the 
cocoons  are  thrown  into  baskets,  which  are  then  placed  in 
the  steaming-box.  When  taken  out,  the  cocoons  are  put 
between  woollen  blankets,  so  that  the  heat  may  be  retained 
and  its  effect  continued  a  little  longer.  After  a  few 
hours  they  are  spread  out  on  tables,  and  shovelled  about 
till  perfectly  dry.  This  last  operation  is  specially  re- 
quisite with  such  cocoons  as  cannot  be  reeled  off  at  once. 
Although  the  killing  of  the  cocoons  by  steam  has  the  great 
advantage  that  there  is  no  fear  of  the  silk  itself  being 
damaged  by  overheating,  still  it  has  certain  defects.  The 
most  serious  are,  that  some  of  the  pupae  burst  and  soil  the 
silk,  and  that  the  fibres  soften  somewhat,  and  tend  to  stick 
together,  rendering  the  subsequent  reeling  more  difficult. 

After  killing,  the  cocoons  are  "  sorted/'  or  divided  into 
classes  of  different  quality.  In  every  piece  of  woven  silk 
the  warp  threads  have  to  bear  the  greatest  strain,  and, 
as  a  rule,  must  appear  on  the  surface  of  the  fabric,  hence 
the  best  cocoons  are  chosen  for  the  warp,  since  they  must 
yield  strong,  smooth,  even,  and  lustrous  fibres.  These 
fibres,  too,  in  the  subsequent  process  of  reeling,  are 
manipulated  somewhat  differently  from  the  weft-fibres. 
The  product  of  this  choice  and  particular  treatment  forms 
the  best  quality  of  silk,  that  is,  warp-silk,  which  is  known 
as  Organzine.  A  somewhat  inferior,  class  of  cocoons  is 
worked  up  to  form  weft-silk,  or  Tram. 

Raw  Silk. — In  the  reeling  process  a  number  of  cocoons 
(4-18)  are  thrown  into  a  basin  of  warm  water,  in  order 
to  soften  the  gummy  envelope  of  the  fibres,  thus  per- 


52 


TEXTILE  FABRICS. 


mitting  their  ready  separation  from  the  cocoon,  and  also 
to  cause  the  subsequent  agglutination  of  whatever  number 
of  fibres  may  be  thrown  together  to  form  a  single  thread. 
During  this  reeling  process  two  threads,  composed  of  an 
equal  number  of  fibres,  are  passed  separately  through  two 
perforated  agate  guides ;  after  being  crossed  or  twisted 
together  at  a  given  point,  they  are  again  separated,  and 
passed  through  a  second  pair  of  guides,  thence  through  the 
distributing  guides  on  to  the  reel.  The  object  of  this 
temporary  twisting  or  crossing  (Fr.  croissage)  is  to  cause 
the  agglutination  of  the  individual  fibres  of  each  thread, 
and  to  aid  in  making  the  latter  smooth  and  round.  The 
unequal  diameter  of  each  fibre  at  different  portions  of  its 
length  is  taken  into  account  by  the  reeler  when  introducing 
new  fibres  into  the  thread  to  replace  those  which  have  run 
out.  The  quality  of  raw-silk  depends  very  much  indeed 
upon  the  care  bestowed  on  the  reeling  process. 

The  loss  through  removal  of  the  external  floss  (bourre) 
varies  from  18-30  %,  according  to  the  cocoons  and  the 
care  bestowed  by  the  worker. 

Reeled-silk  or  raw-silk,  as  it  is  generally  termed,  con- 
stitutes the  raw  material  of  the  English  silk  manufacturer. 
Before  being  used  for  weaving,  two  or  more  of  the  raw- 
silk  threads  are  "  thrown  ?;  together  and  slightly  twisted 
by  the  silk  spinner,  or  "  throwster/7  and  in  this  way  the 
various  qualities  of  Organzine  and  Tram — also  embroidery- 
sewing  silks,  etc. — are  produced. 

A  very  brief  description  of  the  operations  involved  may 
suffice.  The  preliminary  processes  of  "  winding  "  and 
"  cleaning  "  are  followed  by  that  of  "  doubling,"  which 
simply  consists  in  placing  two  threads  ("  singles  ")  side 
by  side,  and  winding  them  together  without  twist.  The 
so-called  "  spinning  J?  of  silk  consists  merely  in  twisting 
the  threads  either  before  or  after  doubling. 

The  "  Tram/7  already  alluded  to,  is  the  product  of  the 
union  of  two  or  more  single  untwisted  threads,  which  are 
then  doubled  and  slightly  twisted. 

"  Organzine  7;  is  produced  by  the  union  of  two  or  more 
single  threads  separately  twisted  in  the  same  direction, 
which  are  doubled  and  then  re-twisted  in  the  opposite 
direction. 

Waste-silk. — This  proceeds  from  perforated  and  double 


SILK. 


53 


cocoons,  and  such  as  are  soiled  in  steaming;  also  the 
extreme  outer  and  inner  portions  of  the  cocoons  :  in  short, 
all  silk  obtained  from  cocoons  in  any  way  soiled  or  unable 
to  yield  a  continuous  thread.  The  killed  chrysalides  can 
be  used  as  a  source  of  oil,  and  the  residue  after  extraction 
may  serve  for  manure. 

All  such  waste-silk  materials  are  washed,  boiled  with 
soap,  and  dried.  They  are  afterwards  carded  and  spun 
somewhat  after  the  manner  of  cotton  and  flax,  and  yield 
the  so-called  Spun  silk.  Schappe  silk  is  a  similar  product, 
made  from  waste  silk  without  previous  boiling. 

Careful  examination  of  the  perforated  cocoons  has  re- 
vealed the  fact  that  their  fibres  are  not  discontinuous. 
The  moth  does  not  eat  its  way  out  of  the  cocoon,  but 
rather  pushes  aside  the  previously  softened  fibres.  At- 
tempts made  to  reel  these  cocoons  by  the  ordinary  methods 
have  failed,  since  the  cocoons  soon  fill  with  water  and 
sink. 

Wild  Silk. — The  most  important  is  the  Tussur  silk 
(Hindustani,  Tusuru,  a  shuttle),  also  called  Tusser,  Tasar, 
Tussore,  and  Tussah.  It  is  the  product  of  the  larva  of  the 
moth  Anther rea  mylitta. 

The  Tussur  moth  is  found  in  nearly  all  parts  of  India, 
where  it  seems  to  feed  on  a  large  variety  of  plants. 
In  some  districts  it  is  reared  by  the  natives.  The  cocoons, 
which  are  much  larger  than  those  of  Bombyx  mori,  are  egg- 
shaped  and  of  a  silvery  drab  colour.  They  are  attached 
to  the  twigs  of  the  food-trees  by  a  peduncle  having  a 
terminal  ring.  The  outer  silk  is  somewhat  reddish,  and 
consists  of  separate  fibres  of  various  length,  while  the 
rest  is  generally  unbroken  to  the  centre  of  the  cocoon. 
The  cocoon  is  extremely  firm  and  hard,  the  fibres  being 
cemented  together  by  a  peculiar  secretion  of  the  animal, 
which  permeates  the  whole  wall  of  the  cocoon,  and  im- 
parts to  it  its  drab  colour.  The  cocoons  are  boiled  and 
carded,  or  even  reeled,  although  this  latter  process  pre- 
sents difficulties.  Silk  plush  is  largely  made  from  carded 
Tussur  silk. 

Other  wild  silks  are,  Eria  silk,  from  Attacus  ricini; 
Muga  silk,  from  Anthercea,  assama;  Atlas  silk,  from  Atta- 
cas  atlas ;  Yama-mai  silk,  from  the  Anthercea  yama-ma'i  of 
Japan,  etc. 


54 


TEXTILE  FABRICS. 


Under  the  microscope  a  raw  mulberry-silk  fibre  appears 
as  a  double  fibre  (Fr.  have)  consisting  of  two  solid  struc- 
tureless cylinders  (Fr.  brin),  more  or  less  united  together 
(Fig.  12) ;  after  "  boiling-off  "  with  soap,  however,  this 
double  fibre  separates  into  a  pair  of  distinct  fibres,  having 
a  more  or  less  irregular,  somewhat  rounded  triangular 
section. 

Wild  silk  is  distinguished  from  mulberry  silk  by  the 
longitudinal  striations  seen  in  each  of  the  double  fibres 
when  under  microscopic  examination  (Fig.  14),  and  by  the 
apparent  contraction  of  the  fibre  at  certain  points.  The 
former  are  due  to  the  fact  that  the  wild-silk  fibre  is  com- 
posed of  a  large  number  of  fibrils,  while  the  latter  appear- 


Fig.  11. — Microscopic  Appearance  of  Tussur  Silk  Fibre. 

ance  is  seen  because  the  more  or  less  flattened  fibres  are 
twisted  at  the  contracted  points. 

Physical  Properties  of  Silk. — The  most  important  are 
its  lustre,  strength,  and  avidity  for  moisture.  One  other 
distinctive  property  which  it  possesses  in  certain  condi- 
tions is  that  of  emitting  a  peculiar  crisp,  crunching  sound 
(Fr.  cri)  when  a  bundle  of  silk  yarn  is  tightly  twisted 
and  pressed  together.  This  peculiar  property  is  called 
the  "  scroop  7  (Fr.  craquant)  of  the  silk,  and  no  doubt 
gives  rise  to  the  rustling  noise  heard  when  two  pieces  of 
silk  fabric  rub  lightly  against  each  other.    The  intensity 


SILK. 


55 


of  the  phenomenon  varies  with  the  nature  of  the  dyeing 
and  mechanical  processes  adopted,  with  the  diameter  and 
twist  of  the  threads,  etc. 

The  property  is  absent  in  raw-silk  and  in  "  boiled-off/' 
or  in  "  souple  "  silk;  it  is  only  manifested  if  the  last  bath 
or  solution  through  which  the  silk  has  passed  contained 
an  acid  salt  or  free  acid.  Silk  which  has  been  worked  in 
a  neutral  or  alkaline  bath — for  example,  a  soap  bath — 
possesses  no  "  scroop/'  No  sufficient  explanation  of  the 
action  of  acid  in  producing  scroop  has  been  given,  but  it 
is  not  improbable  that  acids  cause  the  fibres  to  become 
more  rough  or  irregular  on  the  surface,  so  that  when  sub- 
mitted to  pressure  they  slip  past  each  other  with  a  jerky 
movement. 

When  it  is  desired  to  impart  scroop  to  the  silk  after 
dyeing,  it  is  submitted  to  a  special  treatment.  Very  often 
it  is  first  passed  through  a  weak  soap  bath  or  an  oil 
emulsion,  and  then  into  a  weak  acid  bath,  or  it  is  intro- 
duced into  a  bath  which  is  both  oily  and  acid. 

In  order  to  develop  all  the  qualities  of  softness  and 
brilliancy  of  which  silk  is  capable,  it  is  submitted  (while 
still  in  the  form  of  hanks  of  yarn)  to  the  following  me- 
chanical operations  : — 

Shaking  Out  Silk  (Fr.  secouage). — The  object  of  this 
is  to  open  out  or  beat  out  the  hanks  of  silk,  and  to  give 
the  latter  a  uniform  appearance  by  removing  all  tendency 
to  curl  or  wrinkle.  It  is  generally  performed  after  dry- 
ing, but  if  before,  the  drying  is  greatly  facilitated.  It 
consists  in  hanging  the  hank  of  yarn  on  a  strong  smooth 
wooden  peg  fixed  to  the  wall,  and  inserting  a  smooth 
wooden  rod  in  the  loop,  which  is  then  vigorously  and 
quickly  pulled.  The  point  of  suspension  is  frequently 
changed,  and  the  shaking  out  is  repeated.  The  operation 
may  also  be  done  by  a  machine  of  M.  Cesar  Corron,  St. 
Etienne,  with  the  utmost  regularity. 

Stringing  or  Glossing  Silk  (Fr.  clievillage). — This 
operation,  which  was  originally  only  performed  in  con- 
junction with  the  "  shaking-out  "  for  the  purpose  of 
straightening  the  threads,  and  dressing  the  hanks  after 
diverse  operations  of  the  dye-house,  has  now  acquired  in- 
creased importance,  particularly  in  the  case  of  souples. 
With  these  it  forms  the  final  operation,  the  silk  being 


56 


TEXTILE  FABRICS. 


operated  upon  in  the  dry  state.  Its  object  in  this  case  is 
to  complete  the  separation  of  the  double  silk  fibre  into  its 
constituent  fibres,  and  to  add  lustre. 

The  operation  consists  in  twisting  the  hanks  of  silk 


SILK. 


57 


when  perfectly  dry.  They  are  hung  on  pegs,  as  in  the 
last  operation,  which  it  generally  succeeds.  A  stated  and 
progressive  tension  is  thus  given,  which  adds  softness 
and  brilliancy  to  the  fibres.  This  operation  can  also  be 
performed  with  a  machine,  a  representation  of  which  is 
given  in  Figs.  15  and  16. 

The  stringing  machine  (Fig.  15)  is  composed  of  a  series 
of  horizontal  pegs  A,  which  can  be  made  to  revolve  by 
means  of  the  lever  and  ratchet  l  and  the  cog-wheels  K. 
A  second  series  of  horizontal  rollers  B,  situated  directly 
beneath  the  pegs  A,  are  fixed  on  elbow-shaped  spindles. 
They  are  capable  of  two  movements,  namely,  that  of  re- 
volving on  their  own  axis — i.e.  the  horizontal  axis  of  the 


p 


Fig*.  16. — Details  of  Silk-stringing  Machine. 


elbow — as  loose  pulleys,  and  also  at  right  angles  to  this, 
by  the  revolution  of  the  vertical  spindle  of  the  elbow. 
This  last  movement  is  caused  as  follows  :  Each  spindle  is 
supported  by  a  collar  on  a  box  u,  enclosing  a  toothed- 
wheel,  which  is  revolved  by  a  ratchet ;  this  is  actuated  by 
the  backward  and  forward  movement  of  the  horizontal 
arm  d  imparted  by  the  frame  h,  through  the  medium  of 
the  toothed  wheels  f  and  G  and  the  pulley  e. 

Each  spindle  is  also  capable  of  sliding  up  and  down. 
Attached  to  the  bottom  of  the  roller-pegs  b  (Fig.  16)  are 
the  weights  c,  which  can  either  be  raised  separately  by 
the  jointed  levers  m  pressing  against  the  pulley  v,  or  all 
together  by  means  of  the  handle  R.    When  this  handle 


5* 


TEXTILE  FABRICS. 


is  turned,  the  toothed  wheels  s  (Fig.  15)  cause  the  pulley  p 
to  revolve,  the  counterpoise  o  (Fig.  16)  descends,  and  the 
weights  c,  together  with  spindles  and  roller  pegs  b,  are 
raised. 

Suppose  the  hanks  of  silk  are  slung  over  the  pegs  A 
and  b  ;  by  the  action  of  the  ratchet  and  lever  D  the  roller 
pegs  b  revolve  and  the  hanks  are  twisted,  the  pegs, 
weights,  etc.,  being  at  the  same  time  raised  by  the  shorten- 
ing of  the  hanks.  Automatically  the  movement  of  the  lever 
d  is  reversed,  the  hanks  untwist,  and  are  kept  in  the 
stretched  condition  by  the  descending  weights.  At  a  given 
moment,  namely,  just  when  the  hanks  are  entirely  un- 
twisted, the  lever  l  comes  into  play,  and  causes  a  slight 
rotation  of  the  pegs  A,  so  that  the  hanks  become  suspended 
in  a  fresh  position,  to  be  again  twisted  by  the  action  of  the 
lever  d.  The  whole  of  the  movements  are  automatic,  and 
by  a  few  repetitions  of  this  twisting,  untwisting,  and  dis- 
placement of  the  hanks,  the  operation  is  complete. 

In  some  cases  (as  with  sewing  silks),  stringing  con- 
sists simply  in  twisting  the  hanks  of  silk  as  tightly  as 
possible,  then  placing  the  peg  in  a  locked  position,  and 
leaving  the  hanks  in  this  tightly  twisted  condition  for 
several  hours.  The  operation  may  be  repeated  frequently 
during  from  10-15  days.  Its  object  is  to  give  increased 
lustre. 

Lustring  Silk. — This  operation,  effected  by  means  of  the 
machine  represented  in  Fig.  17,  serves  to  impart  the  maxi- 
mum of  brilliancy  to  the  fibre.  It  also  facilitates  the 
subsequent  winding.  The  dyed  and  dried,  or  sometimes 
incompletely  dried,  silk  is  submitted  to  a  gentle  stretching 
between  two  polished  steel  rollers,  c  and  D,  revolving  in 
the  same  direction,  and  enclosed  in  a  cast-iron  box,  the 
lid  A  and  side  b  of  which  can  be  rapidly  removed  when 
necessary.  During  the  rotation  of  the  cylinders,  steam  at 
a  moderate  pressure  is  allowed  to  enter.  The  stretching 
is  effected  by  drawing  the  roller  c  away  from  d  by  means 
of  the  hook  F,  actuated  by  the  cog-wheels  at  E. 

The  brilliant  mother-of-pearl  lustre  possessed  by  silk 
undoubtedly  gives  it  the  place  of  honour  among  all  tex- 
tile fibres. 

Tenacity  and  Elasticity  of  Silk. — The  specific  gravity 
of  silk  is  1367.    Its  tenacity  and  elasticity  are  remarkably 


SILK. 


great.  The  former  is  said  to  be  little  inferior  to  that  of 
a  good  quality  of  iron  wire  of  equal  diameter,  while  the 
latter  is  such  that  a  silk  fibre  can  be  stretched  014-0  2  of  its 
original  length  without  breaking.  These  properties  are 
taken  advantage  of  in  the  operations  of  shaking  out, 
stringing,  and  lustring,  just  described.  The  finest  silk 
is  proportionately  the  strongest  and  most  tenacious. 
Damp  silk  is  less  tenacious  and  more  elastic  than  dry 
silk. 


Fig*.  17. — Silk-lustring"  Machine, 


If  perfectly  dried  silk  is  wetted  with  water,  it  con- 
tracts about  0'7  per  cent.,  and  still  more  if  the  water 
contains  mineral  or  organic  substances  which  penetrate 
the  fibre  and  cause  it  to  swell  up.  These  effects  take  place 
during  the  various  operations  of  dyeing ;  hence  the  neces- 
sity of  stringing,  stretching,  and  lustring,  above  alluded 
to,  in  order  to  prevent  or  counteract  the  contraction. 

The  tenacity  and  elasticity  of  raw-silk  reside  largely 
in  its  external  coating  of  silk-glue.  By  boiling-off  with 
soap,  it  loses  30  %  of  its  tenacity,  and  45  %  of  its  elas- 
ticity. 


Fig.  18. — Conditioning1  Apparatus. 


SILK, 


61 


These  properties  vary  in  weighted  silk,  according  to  the 
nature  of  the  weighing.  If  the  fibre  is  simply  coated  with 
such  substances  as  gelatin,  albumen,  starch,  etc.,  the 
tenacity  will  be  as  a  rule  increased,  but  if  the  weighting 
materials  employed  penetrate  the  substance  of  the  fibre, 
and  cause  it  to  swell  in  a  greater  or  less  degree,  the 
natural  properties  of  the  silk  will  be  modified  accordingly. 
Some  agents,  like  the  simple  colouring  matters,  have  no 
appreciable  influence,  while  others,  as  astringents  and 
metallic  salts,  when  used  in  large  excess,  gradually  destroy 
the  valuable  properties  of  silk  entirely. 

If  silk  is  heated  to  110°  C.  it  loses  all  its  natural 
moisture,  but  remains  otherwise  quite  unchanged.  Ex- 
posed to  170°  C,  and  higher,  it  soon  begins  to  decompose 
and  carbonise.  If  a  silk  fibre  be  inserted  in  a  flame  it  has 
the  appearance  of  fusing  like  wool,  but  it  does  not  give  off 
quite  such  a  disagreeable  odour. 

Silk  is  a  very  bad  conductor  of  electricity,  and  since 
it  readily  becomes  electric  by  friction,  this  condition,  once 
acquired,  is  very  persistent,  and  is  apt  to  become  a  source 
of  trouble  during  the  mechanical  operations  involved  in 
manufacturing.  The  most  effective  mode  of  overcoming 
the  difficulty  is  to  keep  the  atmosphere  of  the  workrooms 
in  a  suitable  state  of  humidity. 

In  its  boiled-off  and  pure  state  silk  resists  ordinary 
decay  most  thoroughly,  and  it  is  rarely  attacked  by  in- 
sects. 

Conditioning  Silk. — If  raw  silk  be  kept  in  a  humid 
atmosphere  it  is  capable  of  absorbing  30  %  of  its  weight 
of  moisture  without  this  being  at  all  perceptible.  This 
circumstance,  coupled  with  the  high  price  of  raw  silk, 
makes  it  of  very  great  importance  to  those  who  trade  in  it 
to  know  exactly  what  weight  of  normal  silk  there  is  in 
any  given  lot  which  may  be  the  subject  of  commercial  deal- 
ings. To  ascertain  this  information  there  have  been  es- 
tablished, in  the  principal  centres  of  the  textile  industry, 
both  in  this  country  and  on  the  Continent,  so-called  con- 
ditioning establishments,  as  in  Lyons,  Crefeld,  Zurich, 
Bale,  Turin,  Milan,  Vienna,  Paris,  London,  Bradford, 
Manchester,  etc.  etc. 

Fig.  18  shows  the  external  appearance  of  the  essential 
apparatus  of  such  an  establishment,  namely,  the  desicca- 


TEXTILE  FABRICS, 


tor.  It  consists  of  an  enamelled  cylindrical  hot-air  cham- 
ber. One  arm  of  a  fine  balance  sustains  a  crown  of  hooks, 
to  which  are  attached  the  skeins  of  silk  to  be  dried.  The 
suspending  wire  passes  through  a  small  opening  in  the 
cover  of  the  cylinder.  The  other  arm  of  the  balance  carries 
the  ordinary  pan  for  weights. 

Fig.  19  gives  a  vertical  section  of  the  chamber.  Hot 
air  at  110°  C.  enters  by  the  tube  a  from  a  stove  situated 
in  a  cellar  below,  passes  into  the  space  B,  and  thence  by 
thirty-two  vertical  tubes,  t,  placed  between  the  two  con- 
centric cylinders  c  and  d,  it  enters  the  upper  portion  of 
the  inner  cylinder  D.  The  hot  air  descends,  dries  the  silk, 
and  escapes  by  the  tubes  E,  which  communicate  with  the 
exit  flue.  The  apparatus  is  provided  with  a  valve  v,  actu- 
ated by  the  lever  k  (Fig.  18)  for  regulating  or  shutting  off 
the  current  of  hot  air. 

The  air  which  passes  outside  the  brickwork  of  the 
stove,  and  is  thus  heated  only  to  a  moderate  degree,  passes 
upwards  between  the  cylinders  c  and  D  into  the  space  r; 
by  means  of  the  button  l,  which  actuates  a  slide-valve, 
its  entrance  into  the  central  chamber  can  be  regulated. 
By  means,  therefore,  of  the  lever  K  and  the  button  L,  the 
supply  of  hot  and  cold  air  into  the  central  chamber  can  be 
regulated  to  a  nicety,  and  the  temperature  of  the  mix- 
ture is  ascertained  by  the  thermometer  t.  The  button  s 
actuates  the  valve  m,  which  cuts  off  communciation  with 
the  exit  flue  and  stops  the  current  of  air  during  a  final 
weighing  operation. 

Several  hanks  of  silk  are  taken  from  the  bale  to  be 
tested  and  divided  into  three  lots,  in  order  to  be  able  to 
make  two  parallel  determinations,  and  a  third  if  neces- 
sary. The  weight  is  first  rapidly  taken,  under  ordinary 
circumstances,  on  a  fine  balance;  the  hanks  are  then  sus- 
pended in  the  desiccator  and  counterpoised,  and  the  hot 
air  current  is  allowed  to  circulate  till  no  further  loss  of 
weight  takes  place.    One  operation  may  last  from  J-f  hour. 

The  average  loss  of  weight  usually  met  with  is  about 
12  %.  Absolutely  dry  silk  is  not  reckoned  as  the  standard 
article,  but  such  as  contains  about  90  %  dry  silk  and  10  % 
moisture.  The  legal  weight  is  really  obtained  by  adding 
11  %  to  the  dry  weight. 

Chemical  C imposition  of  Silk.—  The  silk  fibre  has  been 


SILK. 


the  subject  of  numerous  chemical  researches,  the  general 
result  of  which  may  be  summed  up  by  saying  that  it  is 
composed  essentially  of  two  distinct  parts  :  first,  that 
constituting  the  central  portion  of  the  fibre,  and  secondly, 
a  coating,  or  envelope,  consisting  apparently  of  a  mix- 
ture of  substances  mostly  removable  by  hot  water,  or,  at 


Fig.  19. — Section  of  Conditioning  Chamber. 


any  rate,  by  solvents  which  have  little  or  no  action  on  the 
central  portion. 

In  order  to  determine  the  character  and  amount  of 
these  several  substances,  Mulder  submitted  raw  Italian 
silk  to  the  successive  action  of  boiling  water,  alcohol,  ether, 
and  hot  acetic  acid,  and  in  this  way  obtained  in  a  com- 
paratively pure  state  the  central  silk  substance,  to  which 
he  assigned  the  name  Fibroin.  The  following  numbers 
give  the  results  of  his  analysis  : — 


64 


TEXTILE  FABRICS. 


Silk  fibre  (fibroin)   

Matters  soluble  in  water 

„        ,,        alcohol  .. 

„        ,,  ether 

,,        ,,        acetic  acid 


Yellow 

White 

Italian  silk. 

Levant  silk. 

53'35 

54*05 

28-86 

28-10 

1-48 

1-30 

o-oi 

0-05 

16-30 

16-50 

100-00 

100  00 

By  a  further  examination  of  the  substances  which  each 
solvent  had  extracted,  he  arrived  at  the  following  more 
detailed  analysis  :- 


Yellow 

White 

Italian  siik. 

Levant  silk. 

Fibroin  ... 

  53-37 

54-04 

Gelatin  ... 

  20-66 

19-08 

Albumen  ... 

  24-43 

25-47 

Wax   

  1-39 

1-11 

Colouring  matter 

  0-05 

o-oo 

Resinous  and  fatty  matter  ... 

  o-io 

0-30 

• 

100  00 

100  00 

Mulder  explains  that  on  evaporating  the  aqueous  solu- 
tion to  dryness,  the  residue  would  not  entirely  redissolve 
in  water.  This  insoluble  portion,  therefore,  and  that 
which  is  dissolved  by  acetic  acid,  has  been  reckoned  as 
albumen.  Exception  has  been  taken  by  Bolley  with  re- 
gard to  the  presence  of  this  albumen,  for  if  it  is  borne 
in  mind  that  the  temperature  employed  in  killing  the 
cocoons,  and  that  of  the  water  used  during  the  reeling  pro- 
cess, is  such  as  to  coagulate  any  albumen  which  might 
possibly  be  present,  it  is  highly  improbable  that  raw  silk 
would  contain  any  soluble  albumen. 

Further,  it  has  been  shown  that  living  cocoons,  which 
have  not  therefore  been  submitted  to  any  steaming  pro- 
cess, but  have  simply  been  opened  and  heated  with  tepid 
wrater,  contain  no  albumen.  Fibroin  itself,  too,  is  known 
to  be  somewhat  soluble  in  strong  acetic  acid,  so  that  it 
may,  on  the  whole,  be  concluded  that  what  Mulder  found 
to  be  soluble  in  acetic  acid  was  not  albumen,  but  altered 
fibroin,  and  that  the  percentage  of  this  latter  substance 
in  silk  which  he  gives,  is  too  low. 

By  heating  raw  silk  for  several  hours  with  water  at 
133°  C,  a  residue  of  fibroin  is  obtained  which,  after  the 
removal  of  fatty  matter  by  ether,  and  colouring  matter  by 


SILK. 


65 


alcohol,  represents  66  %  of  the  weight  of  the  silk.  Even 
this  figure  may  possibly  be  too  low,  since  the  usual  loss 
in  practice  during  the  operation  of  "  boiling-off  "  is 
25-30  %. 

The  percentage  composition  of  pure  Fibroin  has  been 
variously  stated,  probably  owing  to  the  different  hygro- 
metric  states  of  the  fibres  examined.  Cramer  gives  the 
formula  as  C13H23N506. 

Sericin  is  that  portion  of  silk  which  is  soluble  in  warm 
water  and  can  be  precipitated  from  its  solution  by  lead 
acetate.  By  submitting  this  precipitate  to  a  somewhat 
tedious  series  of  operations— such  as  washing  with  water, 
suspending  in  water  and  decomposing  with  sulphuretted 
hydrogen,  filtering,  and  evaporating  the  filtered  solution, 
precipitating  and  extracting  with  alcohol,  then  with  ether 
— it  is  possible  to  obtain  the  essential  constituent  of  the 
external  envelope  of  the  silk  fibre  as  a  colourless,  odour- 
less, tasteless  powder.  It  swells  up  in  cold  water,  and 
is  somewhat  more  soluble  in  hot  water  than  gelatin.  A 
6  %  solution  of  it  gelatinises  on  cooling,  and  its  solutions 
are  precipitated  by  alcohol,  tannic  acid,  and  metallic  salt 
solutions.  Altogether,  its  physical  and  chemical  proper- 
ties are  very  similar  to  those  of  glue  and  gelatin  ;  hence 
sericin  is  often  called  silk-glue,  sometimes  also  silk-gum. 
Its  chemical  composition  is  represented  by  the  formula — 
CI5H55_N508.  _ 

It  is  distinct  from  ordinary  glue,  however,  according 
to  some  observers,  since  when  boiled  with  dilute  mineral 
acids  it  yields  different  products. 

If  the  formula  given  for  fibroin  and  sericin  be  com- 
pared, a  relationship  is  apparent  which  may  be  expressed 
by  the  following  equation  : — 

C15H23N50G  +  O  +  H20  -  C15H25N508 

Fibroin.  Sericin. 

Although  these  formulae  can  only  be  considered  as  repre- 
senting approximately  the  percentage  composition  of  these 
two  bodies,  the  above  comparison  has  been  taken  by  some 
as  an  indication  that  originally — i.e.  at  the  moment  of 
secretion — the  silk  fibre  is  probably  a  homogeneous  sub- 
stance, which,  by  the  action  of  the  air  and  moisture, 
rapidly  becomes  altered  superficially.    This  view  is  sup- 

E 


TEXTILE  FABRICS. 


ported  by  the  observation  that  if  moist  fibroin  be  left 
exposed  to  the  air  for  a  lengthened  period  it  becomes 
partially  soluble  in  water.  Bolley  and  Rosa  have  found 
also  that  the  silk-bags  taken  from  living  worms  are  com- 
posed almost  entirely  of  fibroin,  since  only  1'7  % 
is  soluble  in  boiling  water,  and  the  elementary  analysis 
is  consistent  with  the  formula  of  fibroin.  The  physiolo- 
gical studies  of  Duseigneur,  and  especially  his  examination 
of  the  transverse  section  of  the  silk-bag,  already  alluded 
to,  appear  to  contradict  this  view. 

Influence  of  Reagents  on  Silk. — In  contact  with  various 
liquids  silk  not  only  absorbs  them  rapidly,  on  account  of 
its  great  porosity,  but  sometimes  retains  them  with  ex- 
treme tenacity;  this  is  the  case,  e.g.  with  alcohol  and  acetic 
acid.  For  the  same  reason  it  has  great  aptitude  for  fixing 
mordants  and  colouring  matters. 

Action  of  Water  on  Silk. — Prolonged  boiling  with  water 
removes  from  raw  silk  its  silk-glue,  but  it  has  little  effect 
upon  the  fatty,  waxy,  and  colouring  matters  present.  The 
tenacity  of  the  fibre  is  reduced  even  more  than  by  the 
ordinary  methods  of  ungumming  with  soap  solutions.  A 
similar  solvent  action  is  exercised  by  all  liquids ;  for  this 
reason  it  is  not  customary  to  mordant  silk  with  hot  solu- 
tions, and  the  dyeing  is  conducted  at  a  temperature  as 
low  as  circumstances  will  permit. 

Action  of  Acids  on  Silk. — Speaking  generally,  con- 
centrated mineral  acids  rapidly  destroy  silk,  but  if 
sufficiently  diluted  their  action  is  insensible.  Warm  dilute 
acids,  however,  dissolve  the  sericin  of  raw  silk,  and  hence 
these  may  be  used  in  ungumming  (soupling).  Concen- 
trated sulphuric  acid  dissolves  silk,  giving  a  viscous  brown 
liquid ;  on  diluting  the  latter  with  water  a  clear  solution 
is  obtained,  from  which  the  fibroin  is  precipitated  on  the 
addition  of  tannic  acid. 

Concentrated  nitric  acid  also  rapidly  destroys  silk; 
but  if  diluted,  the  latter  is  only  slightly  attacked  and 
coloured  yellow,  in  consequence  of  the  formation  of  xan- 
thoproteic acid.  This  reaction  is  made  use  of  in  distin- 
guishing silk  from  vegetable  fibres.  Formerly  it  was  also 
utilised  in  dyeing,  but  the  method  is  not  to  be  commended, 
since  the  colour  is  produced  at  the  expense  of  the  silk 
itself,  which  must  inevitably  be  weakened  by  the  process. 


SILK. 


Hydrochloric  acid,  if  applied  in  the  gaseous  state, 
destroys  the  fibre  without  liquefying  it,  but  a  concen- 
trated aqueous  solution  readily  dissolves  it.  Hydrochloric 
acid  38°  Tw.  (Sp.  Gr.  ri9)  when  applied  cold,  dissolves 
an  equal  weight  of  silk  without  even  then  being  saturated. 
Dilute  hydrochloric  acid  has  no  sensible  action,  except 
upon  the  sericin  of  raw  silk,  which  it  more  or  less  removes. 

Phosphoric  and  arsenic  acids  in  dilute  (5  %)  aqueous 
solution  act  like  other  weak  acids  in  removing  the  sericin 
from  raw  silk,  and  have  been  proposed  as  ungumming 
agents  instead  of  soap,  but  they  are  not  used  in  practice. 

Permanganic  acid,  either  in  the  free  state  or  in  com- 
bination with  potassium,  acts  energetically  on  silk;  it 
oxidises  and  colours  the  fibre  brown  by  deposition  of 
hydrated  manganic  oxide.  If  this  be  removed  by  im- 
mersion in  a  solution  of  sulphurous  acid,  the  silk  is  left 
in  a  remarkably  pure  white  condition.  Although  recom- 
mended on  this  account  for  bleaching  silk,  it  is  not  alto- 
gether suitable,  since  the  silk  thus  bleached  always  has  a 
tendency  to  become  yellowish  under  the  influence  of  alkalis. 
Sulphurous  acid  is  used  in  bleaching  silk. 
Chromic  acid  and  chromates,  like  permanganic  acid, 
oxidise  silk,  leaving  the  fibre  of  a  pale  olive  tint. 

The  action  of  organic  acids  on  silk  has  been  little 
studied;  it  varies,  no  doubt  considerably,  according  to 
their  concentration,  temperature,  etc. 

Hot  dilute  organic  acids  remove  the  sericin  from  raw 
silk  but  do  not  affect  the  fibroin  much.  Cold  glacial  ace- 
tic acid  removes  the  colouring  matter  from  yellow  raw-silk 
without  dissolving  the  sericin.  Silk  is  entirely  dissolved 
when  heated  under  pressure  with  acetic  acid. 

Action  of  Alkalis  on  Silk.— Concentrated  solutions  of 
caustic  soda  and  potash  rapidly  dissolve  raw-silk,  especi- 
ally is  applied  warm. 

Caustic  alkalis,  sufficiently  diluted  so  as  not  to  act  ap- 
preciably upon  the  fibroin,  will  dissolve  off  the  sericin, 
and  have  been  tried  as  ungumming  agents.  For  ordinary 
use,  however,  they  must  be  avoided,  since  the  silk  is 
always  left  impaired  in  whiteness  and  brilliancy. 

Pure  ammonia  solution,  even  if  used  warm,  has  no 
sensible  action  on  boiled-off  silk,  but  if  it  is  at  all  impure 
the  silk  becomes   dull  and   dirty   from  absorbed  tarry 


68 


TEXTILE  FABRICS. 


matter.  Ammonia  seems  to  favour  the  absorption  by  silk 
of  salts  of  calcium,  magnesium,  etc. 

Alkaline  carbonates  act  like  the  caustic  alkalis,  but  in 
a  less  energetic  manner,  and  they  are  not  employed  as 
ungumming  agents.  Of  all  alkaline  solutions,  those  of 
soap  have  the  least  injurious  effect.  When  used  hot,  they 
readily  remove  the  sericin  from  raw  silk,  and  leave  the 
fibroin  lustrous  and  brilliant ;  hence  soap  is  par  excellence 
the  ungumming  agent  employed.  Borax  acts  somewhat 
like  soap,  but  cannot  replace  it  in  practice. 

If  raw  silk  be  steeped  for  twenty-four  hours  in  clear, 
cold  lime-water,  it  swells  up  considerably,  the  lime  seem- 
ing to  have  a  strong  softening  action  on  the  sericin ;  when 
this  is  removed  by  dilute  acid  and  a  subsequent  soap  bath, 
the  fibroin  seems  not  to  have  suffered  otherwise  than  by  the 
loss  of  its  natural  brilliancy.  Prolonged  contact,  how- 
ever, with  lime-water  renders  silk  brittle  and  disorganised. 

Chlorine  and  hypochlorites  attack  and  destroy  silk 
rapidly,  and  cannot  be  used  as  "bleaching  agents.  Ap- 
plied in  weak  solutions,  with  subsequent  exposure  of  the 
fibre  to  the  air,  they  cause  the  silk  to  have  an  increased 
attraction  for  certain  colouring  matters. 

Action  of  Metallic  Salts  on  Silk. — If  silk  is  steeped 
in  cold  solutions  of  several  metallic  salts,  e.g.  of  lead, 
tin,  copper,  iron,  aluminium,  etc.,  it  absorbs  and  even 
partly  decomposes  them,  so  that  less  soluble  basic  salts 
remain  in  union  with  the  fibre.  The  methods  of  mordant- 
ing silk  wTith  aluminium,  tin,  and  iron  salts  depend  upon 
this  fact.  Sometimes,  as  in  the  case  of  ferric  and  stannic 
salts,  the  quantity  of  basic  salt  which  may  be  precipitated 
on  the  fibre  is  sufficient  to  serve  as  weighting  material. 

Concentrated  zinc  chloride,  138°  Tw.  (Sp.  Gr.  1'69), 
made  neutral  or  basic  by  boiling  with  excess  of  zinc 
oxide,  dissolves  silk,  slowly  if  cold,  but  very  rapidly  if 
heated,  to  a  thick  gummy  liquid.  This  reagent  may  serve 
to  separate  or  distinguish  silk  from  wool  and  the  vegetable 
fibres,  since  these  are  not  affected  by  it.  If  water  be  added 
to  the  zinc  chloride  solution  of  silk,  the  latter  is  thrown 
down  as  a  flocculent  precipitate.  If  this  is  washed  free 
from  zinc  salt  and  dissolved  in  ammonia,  it  is  said  that 
the  solution  may  serve  to  cover  cotton  and  other  vegetable 
fibres  with  a  coating  of  silk  substance.    Dried  at  110°-115° 


SILK. 


69 


C,  the  precipitate  acquires  a  vitreous  aspect,  and  is  no 
longer  soluble  in  ammonia. 

An  ammoniacal  solution  of  cupric  hydrate  dissolves 
silk,  the  solution  not  being  precipitated  by  neutral  salts, 
sugar,  or  gum,  as  is  the  case  with  the  analogous  solution 
of  cotton.  An  ammoniacal  solution  of  nickel  hydrate  also 
dissolves  silk. 

A  most  excellent  solvent  for  silk  is  an  alkaline  solution 
of  copper  and  glycerine,  made  up  as  follows  :  dissolve 
16  g.  copper  sulphate  in  140-160  c.c.  distilled  water,  and 
add  8-10  g.  pure  glycerine  (Sp.  Gr.  1'24);  a  solution  of 
caustic  soda  is  dropped  gradually  into  the  mixture  till 
the  precipitate  at  first  formed  just  re-dissolves;  excess  of 
NaOH  must  be  avoided.  This  solution  does  not  dissolve 
either  wool  or  the  vegetable  fibres,  and  may  serve,  there- 
fore, as  a  distinguishing  test. 

Action  of  Colouring  Matters  on  Silk. — Generally 
speaking,  silk  has  a  very  great  affinity  for  the  monogenetic 
colouring  matters.  It  can  be  dyed  direct  with  the  aniline 
colours,  for  example,  with  the  greatest  facility.  It  has, 
however,  little  attraction  for  mineral  colouring  matters. 

An  examination  of  sections  of  dyed  silk  reveals  the  fact 
that  the  colouring  matter  (or  the  mordant)  penetrates  the 
substance  of  the  silk  fibre  to  a  greater  or  less  degree, 
according  to  the  solubility  of  the  colouring  matter,  the 
duration  of  the  dyeing  process,  and  the  temperature  em- 
ployed. If  the  silk  is  dyed  only  for  a  short  time,  a  section 
of  the  fibre  shows  an  external  concentric  zone  of  colour, 
while  if  the  dyeing  operation  is  continued  sufficiently  long, 
it  is  coloured  right  to  the  centre.  If  a  mixture  of  two 
colouring  matters  be  applied,  either  simultaneously  or 
successively,  both  are  absorbed,  the  more  soluble,  or  that 
which  has  been  allowed  to  act  longest,  penetrating  the 
fibre  most  deeply.  Externally  a  mixed  effect  is  produced 
in  this  case,  but  a  section  of  the  fibre  reveals  in  most 
cases  two  concentric  zones  of  colour.  Silk  thoroughly  mor- 
danted with  a  ferric  salt  presents  in  section  a  uniform 
yellow  tint;  if  dyed  subsequently  in  an  acidified  solution 
of  potassium  ferrocyanide,  the  ferric  oxide  deposited  in 
the  silk  gives  place  to  Prussian  blue,  at  first  in  the  outer 
portions  only,  but  by  degrees  even  in  the  centre,  especially 
if  the  temperature  of  the  bath  be  raised.    A  similar  effect 


To 


TEXTILE  FAB  ETC  S. 


is  produced  if  a  bath  of  tannin  be  substituted  for  that  of 
potassium  ferrocyanide.  It  is  indeed  difficult  to  say  what 
number  of  substances  might  be  successively  absorbed  by 
the  silk,  and  penetrate  it  either  by  juxtaposition  or  by 
reacting  upon  each  other. 

The  action  of  colouring  matters  on  raw  silk  is  similar ; 
but  in  many  cases,  as  in  the  black  dyeing  of  souples,  the 
colouring  matter  is  situated  principally  in  the  external 
silk-glue  which,  becoming  brittle  through  the  large  amount 
of  foreign  matter  it  then  contains,  breaks  up  and  assumes 
the  form  of  microscopic  beads. 


71 


CHAPTER  V. 

COTTON  BLEACHING. 

Object  of  Bleaching. — Raw  cotton  is  contaminated  with 
several  natural  impurities,  and  although  these  are  com- 
paratively small  in  amount,  they  impair  the  brilliancy  of 
the  white  belonging  to  pure  cellulose.  Hence  cotton  yarn 
as  it  leaves  the  spinner  has  invariably  a  soiled  or  greyish 
colour.  When  such  yarn  is  woven  it  is  still  further  con- 
taminated with  all  the  substances  (amounting  sometimes  to 
30  %)  which  are  introduced  during  the  sizing  of  the 
warps,  as  china  clay,  grease,  etc. 

Bleaching  consists  in  the  complete  decolorising  or  re- 
moval of  all  these  natural  and  artificial  impurities,  either 
for  the  purpose  of  selling  the  goods  in  the  white  state, 
or  in  order  to  make  them  suitable  for  being  dyed  light, 
delicate,  and  brilliant  colours. 

Bleaching  Raw  Cotton. — Although  raw  cotton  is  now 
largely  dyed,  it  is  seldom  bleached  in  this  form,  because  it 
becomes  more  or  less  matted  together.  As  a  rule,  the  only 
treatment  previous  to  dyeing  which  it  receives  is  that  of 
boiling  with  water  until  thoroughly  wetted. 

Bleaching  Cotton  Yarn. — When  cotton  yarn  has  to  be 
dyed  black  or  dark  colours,  it  is,  as  a  rule,  not  bleached, 
but  merely  boiled  with  water  till  thoroughly  softened  and 
wetted.  For  light  colours  the  dyer  frequently  effects  a 
rapid,  though  perhaps  more  or  less  incomplete,  bleaching 
by  passing  the  wetted  yarn  through  a  boiling  weak  solu- 
tion of  soda-ash,  then  steeping  it  for  a  few  hours  in  a  cold 
weak  solution  of  chloride  of  lime  or  hypochlorite  of  soda. 
It  is  then  washed  in  water,  steeped  in  dilute  hydrochloric 
acid,  and  finally  well  washed. 

A  more  complete  and  thorough  bleaching  is  that 
effected  by  the  operations  now  to  be  briefly  described. 

"  Warps  J?  are  loosely  chained  by  hand  or  machine,  in 
order  to  reduce  their  length.    If  the  yarn  is  in  hanks 


72 


TEXTILE  FABRICS. 


it  is  either  retained  in  that  form,  or  linked  together  to 
form  a  chain,  the  latter  being  the  better  and  more  econo- 
mical method. 


Fig.  20. — Apparatus  for  Chemicking,  Souring,  and  Washing. 


L  Ley  boil. — For  1,500  kg.  yarn,  boil  six  hours  with 
2,000  litres  water  and  300  litres  caustic  soda  32°  Tw.  (Sp. 
Gr.  1*16)  ;  steep  in  water  for  forty-five  minutes  and  wash. 


COTTON  BLEACHING. 


73 


2.  Chemicking.— Steep  the  yarn  for  two  hours  under 
sieve  in  a  solution  of  bleaching  powder  2°  Tw.  (Sp.  Gr. 
101),  then  wash  for  half  an  hour  under  sieve. 

3.  Souring.— Steep  the  yarn  for  half  an  hour  under  sieve 
in  dilute  sulphuric  acid  1°  Tw.  (Sp.  Gr.  1'005),  then  wash 
for  half  an  hour  under  sieve  and  afterwards  through  wash- 
ing machine. 

If  the  yarn  is  intended  to  remain  white  and  not  to 
be  dyed,  it  is  run  through  a  so-called  "  bluing  "  machine 
with  hot  soap  solution  and  blue  (ultramarine,  etc.),  then 
hydro-extracted  and  dried. 

When  bleaching  cotton  thread,  owing  to  its  closer  tex- 
ture, the  first  three  operations  are  repeated 

The  boiling  (also  called  "  bowking  "  or  "  bucking  ") 
with  caustic  soda  solutions  takes  place  in  large  iron 
boilers  or  "  Hers."  These  are  either  open  or  provided 
with  a  lid  capable  of  being  screwed  down,  in  order  to 
be  able  to  boil  with  a  slight  pressure  of  steam. 

The  usual  order  of  procedure  is  first  to  fill  the  kier 
with  the  yarn,  and  after  blowing  steam  through  for  an 
hour  or  so,  to  run  in  the  soda  solution  and  boil  for  10-12 
hours. 

The  operations  of  chemicking,  souring  and  washing 
under  sieve,  are  carried  out  by  means  of  the  arrangement 
shown  in  Fig.  20.  It  consists  of  a  stone  tank  e,  with  a 
false  bottom  f,  and  a  valve  G,  communicating  with  the 
cistern  d  below ;  b  is  the  shaft  which  works  the  pump  c ; 
f'  is  a  movable  perforated  drainer  or  sieve  covering  the 
whole  surface  of  the  tank  e  ;  a  is  a  winch  for  drawing  the 
chain  of  yarn  into  the  tank.  Supposing  the  tank  to  be 
packed  with  yarn,  the  pump  is  set  in  motion,  the  liquid  in 
D  is  thus  raised  to  the  sieve  f',  whence  it  showers  down  on 
the  yarn  below.  It  filters,  more  or  less  rapidly,  through 
the  yarn  and  collects  again  in  the  tank  d  to  circulate  as 
before. 

Complete  separate  arrangements  of  this  kind  are  re- 
quired both  for  chemicking  and  for  souring,  but  the  wash- 
ing under  sieve  is  performed  in  either  set  of  tanks  as 
required,  it  being  only  necessary  to  stop  the  pump,  close 
the  valve  G,  and  allow  water  to  flow  from  a  tap  placed 
over  the  sieve,  and  to  escape  at  the  bottom  of  the  tank  E 
by  a  separate  plug-hole  into  the  nearest  drain.    The  final 


74 


TEXTILE  FABRICS. 


washing  after  souring  is  best  given  by  means  of  a  square 
beater  washing  machine. 

The  "  bluing  "  machine  referred  to  is  essentially  the 
same  in  construction  as  the  final  washing  machine,  the 
main  difference  being  that  the  square  beater  is  replaced  by 
a  round  roller,  and  that  the  upper  squeezing  roller  is 
covered  with  cotton  rope  and  rests  loosely  with  its  own 
weight  on  the  lower  one.  As  the  cotton  yarn,  soaked  with 
soap  solution  and  blue,  passes  rapidly  between  the  squeez- 
ing rollers,  the  irregularities  produced  by  the  plaiting  or 
linking  impart  a  constant  jumping  motion  to  the  upper 
roller,  and  the  liquid  is  effectually  beaten  and  pressed 
into  the  heart  of  the  yarn,  thus  enhancing  considerably 
the  purity  of  the  white. 

Bleaching  Cotton  Cloth  or  Calico. — The  mode  of  bleach- 
ing is  varied  according  to  the  immediate  object  for  which 
the  bleached  calico  is  intended ;  thus,  one  may  distinguish 
between  the  Madder-bleach,  the  Turkey-red-bleach,  and 
the  Market-bleach. 

Madder-bleach  is  the  most  thorough  kind  of  calico- 
bleaching,  and  was  originally  so-called  because  it  was 
found  specially  requisite  for  those  goods  which  had  to 
be  printed  and  subsequently  dyed  with  madder.  Its  ob- 
ject is  to  effect  the  most  complete  removal  possible  of 
every  impurity  which  can  attract  colouring  matter  in  the 
dye-bath,  so  that  the  printed  pattern  may  ultimately 
stand  out  in  clear  and  bold  relief  on  a  white  background 
of  unstained  purity.  Although  the  madder-bleach  is  in 
general  use  among  calico-printers,  it  may  be  also  adopted 
by  dyers  whenever  the  calico  is  to  be  dyed  subsequently 
in  light  and  delicate  colours,  or  if  absolute  freedom  is 
desired,  from  any  impurity  which  resists  the  fixing  of 
the  colouring  matter  to  be  applied. 

Stamping  and  Stitching. — For  the  purpose  of  subse- 
quent recognition,  the  ends  of  each  piece  are  marked  with 
letters  and  figures,  by  stamping  them  with  gas-tar  or 
other  substance  capable  of  resisting  the  bleaching  process. 
The  pieces  are  then  stitched  together,  end  to  end,  by 
machinery. 

Singeing. — This  operation  consists  in  burning  off  the 
nap  or  loose  fibres  which  project  from  the  surface  of  the 
cloth,  since  these  interfere  with  the  production  of  fine 


76  TEXTILE  FABRICS. 

impressions  during  the  printing  process.  It  is  performed 
by  rapidly  passing  the  cloth  in  the  open  width  over  red- 
hot  plates  or  cylinders,  or  over  a  row  of  gas  flames. 

Fig.  21  illustrates  the  Mather  and  Piatt  plate  singeing 
machine.  By  means  of  a  furnace,  two  copper  plates  are 
kept  at  a  red  heat,  and  the  piece  is  passed  rapidly  over 
them  in  the  direction  shown  by  the  arrows.  Immediately 
after  passing  the  plates  the  piece  passes  down  into  a 
trough  of  water  so  that  any  adhering  sparks  are  at  once 
extinguished.  After  this  the  piece  is  squeezed  and  "  fliped 
down  "  in  the  usual  manner.  The  chief  difficulty  with 
these  machines  is  to  prevent  the  plates  rapidly  cooling 
at  the  place  where  the  piece  touches  them.  In  the  machine 
illustrated  this  is  avoided  by  traversing  the  bars  which 
press  the  cloth  down  on  to  the  plate,  so  that  the  piece  is 
continually  changing  its  position  whilst  every  portion  of 
the  surface  of  the  plate  is  utilised  in  turn.  In  another 
machine  the  same  end  is  gained  in  a  somewhat  clumsier 
manner  by  using  tubular  plates  through  which  the  flames 
from  the  furnace  pass,  the  plates  themselves  being  con- 
tinually rotated.  The  amount  of  singe  is  regulated  by 
raising  or  lowering  the  bars  guiding  the  piece,  which  is 
done  by  means  of  the  chain  shown.  There  is  also  a  sheet 
metal  hood  which  covers  the  greater  portion  of  the  machine 
and  is  provided  with  a  flue  through  which  the  products  of 
combustion  are  led  away. 

This  method  of  singeing  is,  as  a  rule,  only  now  used 
for  thick  or  heavy  cloth,  and  for  light  goods  is  entirely 
superseded  by  gas  singeing,  a  typical  machine  for  which 
work  is  shown  in  Fig.  22. 

In  this,  the  Mather  and  Piatt  machine,  the  gas  flame 
bears  directly  against  the  cloth,  and  is  not  used  to  heat 
bars  as  in  some  cases.  The  cloth  is  fed  from  the  right  of 
the  illustration,  and,  after  passing  tensioning  bars,  is 
passed  across  a  slot  in  the  underside  of  an  exhausting 
chamber  connected  with  a  fan,  so  that  the  flame  from  the 
burner  immediately  below  is  drawn  through  the  cloth  by 
the  current  of  air.  The  burner  and  the  above-mentioned 
exhausting  chamber  are  shown  on  an  enlarged  scale  at  the 
right  of  Fig.  22,  in  which  the  small  arrows  show  the  pas- 
sage of  the  gas  and  flame,  whilst  a  larger  arrow  points 
to  a  water  jacket  which  surrounds  the  exhausting  cham- 


78 


TEXTILE  FABRICS. 


ber,  and  through  which  a  current  of  cold  water  is  main- 
tained. As  a  rule,  one  burner  working  on  this  principle 
is  enough  to  singe  light  fabrics,  but  in  case  it  is  neces- 
sary to  thoroughly  singe  both  sides,  two  burners  are  used, 
as  shown  in  the  illustration.  The  cloth  passes  over  one, 
is  turned  by  passing  round  two  guide  rods,  and  then  pre- 
sents its  other  face  to  a  second  burner.  It  then  passes 
through  the  usual  trough  of  water  and  out  of  the  machine 
in  the  direction  marked  by  the  arrows. 

The  preliminary  work  of  stamping,  stitching,  and 
singeing  is  succeeded  by  the  bleaching  operations  proper, 
which,  for  24,000  kg.  =  23*6  tons  cloth  and  with  low  pres- 
sure kiers,  may  be  summarised  as  follows  : — 

1.  Wash  after  singeing. 

2.  Lime-boil:  1,000  kg.  (2204-6  lb.)  lime,  boil  12  hours  :  wash. 

3.  Lime-sour:  hydrochloric  acid,  2°  Tw.  (Sp.  Gr.  1*01)  ;  wash. 

4.  Ley-boils:  1st,  310  kg.  (749-4  lb.)  soda  ash,  boil  3  hours. 

2nd,  860  kg.  (1896  lb.)  soda  ash,  380  kg.  resin, 
190  kg.  (418*9  lb.)  solid  caustic  soda,  boil  12 
hours. 

3rd,  380  kg.  (837*74  lb.)  soda  ash,  boil  3  hours;  wash. 

5.  Chemicking  :   bleaching  powder  solution,  J° — J°  Tw.  (Sp.  Gr. 

1  00125— 1-0025)  wash. 

6.  White-sour  :  hydrochloric  acid,  2°  Tw.  (Sp.  Gr.  l'Ol),  pile  1 — 3 

hours. 

7.  Wash,  squeeze  and  dry. 

1.  Wash  after  Singeing. — The  object  of  this  opera- 
tion is  to  wet  out  the  cloth  and  make  it  more  absorbent, 
also  to  remove  some  of  the  weaver's  dressing.  This  w.is 
formerly  effected  by  simply  steeping  the  cloth  in  water 
for  several  days  until,  by  the  fermentation  induced,  the 
starchy  matters  were  rendered  more  or  less  soluble.  At 
present,  printers7  calicoes  arc  not,  as  a  rule,  heavily  sized, 
and  a  simple  wash  is  sufficient.  The  pieces  are  drawn 
direct  from  the  adjacent  singeing  house,  guided  by  means 
of  white  glazed  earthenware  rings  ("  pot-eyes  J'),  through 
the  washing  machine ;  they  are  at  once  plaited  or  folded 
down  on  the  floor  and  there  allowed  to  lie  "  in  pile  "  for 
some  hours  to  soften.  By  this  first  operation,  frequently 
called  "  grey-washing,'7  the  pieces,  hitherto  in  the  open 
width,  assume  the  chain  form,  which  in  many  cases  they 
retain  throughout  the  whole  of  the  succeeding  operations 


COTTON  BLEACHING. 


79 


2.  Lime-boil  ("  Lime-bowk  The  pieces  are  now  run 
through  milk  of  lime,  a  portion  of  which  they  absorb. 
They  are  then  passed  by  overhead  winches  into  a  kier,  and 
there  plaited  down  and  well  packed. 

The  most  modern  method  is  that  which  is  made  possible 
by  the  Mather  and  Piatt  kier  shown  in  Fig.  23.    The  goods 


Fig.  23.— Longitudinal  Section  of  the  Mather  Patent  Kier. 


are  run  into  trucks,  and  these  can  be  filled  whilst  pre- 
ceding pieces  are  in  the  kier.  When  a  change  is  to  be 
made,  the  cover  of  the  kier  (shown  to  the  right  of  the 
illustration)  is  drawn  up  by  a  winch  and  chain.  Rails  run 
right  up  to  the  mouth  of  the  kier  and  are  continued  in- 
side, so  that  the  trucks  can  be  run  in  or  out  without  much 
labour.    Each  truck  has  a  perforated  bottom,  and  two,  as 


80 


TEXTILE  FABRICS. 


a  rule,  are  in  the  kier  at  a,  time.  When  the  kier  is  again 
closed  steam  is  admitted,  and  then  the  liquor  is  run  in, 
falling  on  two  corrugated  discs  and  then  in  a  spray  to 
each  truck.  It  flows  down  through  the  material,  and  is 
drained  off  at  the  bottom,  to  be  again  pumped  up  and 
delivered  above.  The  arrows  show  the  direction  of  the 
liquor  to  the  centrifugal  pump  below  the  kier. 

In  kiers  specially  designed  for  cloth  bleaching  the 
cloth  is  treated  in  open  width,  and  either  boiled  whilst 
on  a  perforated  drum  or  passed  backwards  and  forwards 
between  two  drums  whilst  in  the  kier. 

The  essential  action  of  boiling  with  lime  is  to  decom- 
pose the  fatty,  resinous,  and  waxy  impurities  present  in 
the  fabric.  They  are  not  removed,  but  remain  attached 
to  the  fibre  as  insoluble  liihe  soaps,  which  can,  however, 
be  readily  removed  by  the  subsequent  processes. 

The  colouring  matter  of  the  fibre  is  modified,  and  any 
alumina  present  is  also  attacked. 

No  doubt,  caustic  alkalis  would  also  decompose  and 
at  once  render  soluble  the  fatty  impurities,  but  lime  is 
cheaper,  and  is  said  to  attack  the  resinous  matters  more 
energetically. 

3.  Lime-sour. — This  operation,  also  called  the  "  grey 
sour, ' '  is  immediately  preceded  by  a  washing  of  the  pieces 
as  they  come  out  of  the  lime-boil.  It  consists  in  washing 
the  pieces  with  dilute  hydrochloric  acid.  During  this 
process  the  insoluble  lime-soaps,  resulting  from  the  lime- 
boil,  are  decomposed  and  the  lime  is  removed ;  any  other 
metallic  oxides  present  are  also  dissolved  out,  and  the 
brown  colouring  matter  is  loosened.  Hydrochloric  acid 
is  preferred  to  sulphuric  acid  because  it  forms  a  more 
soluble  compound  with  the  lime.  Care  must  be  taken  to 
maintain  the  strength  of  the  dilute  acid  as  uniform  as 
possible,  both  by  having  a  regular  flow  of  fresh  acid  from 
a  stock  cistern,  and  by  making  occasionally  rapid  acidi- 
metrical  tests.  After  souring,  it  is  advisable  not  to  leave 
the  pieces  long  in  their  acid  state,  for  fear  of  the  ex- 
posed portions  becoming  tender,  but  to  wash  them  as  soon 
as  convenient.  It  is  very  essential,  too,  that  this  washing 
be  as  complete  as  possible,  otherwise  a  tendering  action 
may  take  place  during  the  following  process. 

4.  Ley-  or  Lye-boil. — The  object  of  this  operation  is 


COTTON  BLEACHING. 


81 


to  remove  the  fatty  matters  still  remaining  on  the  cloth. 
The  fatty  matters  having  been  decomposed  during  tne 
lime-boil,  and  the  lime  having  been  removed  from  the 
lime-soaps  by  the  souring,  the  fatty  acids  remaining  on 
the  cloth  are  readily  dissolved  off  by  boiling  with  alkaline 
solutions.  The  brown  colouring  matters  are  also  chiefly 
removed  at  this  stage.  The  boiling  takes  place  in  exactly 
the  same  kind  of  kiers  as  those  used  for  the  lime-boil. 
Other  kiers  besides  the  above,  however,  are  frequently 
used  for  both  operations. 

In  the  so-called  k'  vacuum  kiers,"  perfect  penetration  of 
the  cloth  by  the  liquors  is  obtained  by  first  pumping  out 
the  air  from  the  kier  before  admitting  the  liquors. 

Fig.  24  gives  the  section  of  a  modern  "  injector  "  kier  A, 
filled  with  cloth ;  b  b  are  the  steam  pipes,  c  is  the  in- 
jector, and  d  the  circulating  pipe;  f  is  the  liquor  pipe, 
by  which  water  or  other  liquid  may  be  admitted ;  E  e  the 
draw-off  valve  and  waste  pipe.  The  kier  being  suitably 
filled  with  cloth  and  liquor,  whenever  the  steam  is  turned 
on,  the  vacuum  produced  by  its  condensation  in  c  with- 
draws the  liquor  from  the  kier  and  causes  it  to  ascend  the 
pipe  d,  to  be  at  once  showered  over  the  pieces  at  G.  A 
portion  of  the  liquid  may  temporarily  collect  at  H,  but 
it  soon  percolates  or  is  drawn  through  the  cloth  to  the 
bottom,  again  to  enter  the  injector.  A  continual  circula- 
tion of  the  liquid  is  thus  maintained. 

If  open  or  low-pressure  kiers  are  used,  similar  to  that 
referred  to  in  cotton-yarn  bleaching,  the  boiling  is  con- 
tinued for  10-12  hours;  with  the  injector  kier  and  steam 
at  50  lb.  pressure,  3-4  hours'  boiling  may  be  sufficient. 

Some  bleachers  boil  1-3  hours  with  soda-ash  alone,  both 
before  and  after  the  resin  boil,  using  1-2  kg.  soda-ash  per 
100  kg.  calico.  The  first  soda-ash  boil,  though  not  abso- 
lutely necessary,  is  advisable,  in  order  to  neutralise  any 
traces  of  acid  accidentally  left  in  the  cloth  from  the  sour- 
ing. Another  plan  to  avoid  tendering,  is  to  let  the  goods 
steep  in  a  weak  soda-ash  solution  for  a  short  time,  and 
then  to  draw  it  off  again  before  commencing  the  boiling 
operation  with  "  resin-soap."  This  is  termed  "  sweeten- 
ing "  the  goods. 

The  boiling  with  resin-soap  is  a  very  special  feature 
in  the  madder-bleach.    Experiment  has  shown  that  resin- 
F 


82 


TEXTILE  FABRICS. 


soap  removes,  better  than  any  other  substance  which  has 
been  tried,  certain  matters,  which  would  subsequently 
attract  colouring  matter  in  the  dye-bath. 

The  boiling  with  soda-ash  solution  after  the  "  resin 


Fig-.  24.  -  Section  of  Injector  Kier. 


COTTON  BLEACHING. 


83 


boil  "  is  useful,  in  order  to  ensure  the  complete  removal 
of  fatty  matters  and  undissolved  resin. 

Since  the  cloth  is  very  liable  to  contract  iron  stains  if 
left  in  the  kier  too  long  after  the  alkaline  liquor  has 
been  drained  away,  it  is  well  to  wash  immediately  after 
the  ley-boils. 

5.  Chemicking. — After  all  the  previous  operations  the 
cloth  still  retains  a  faint  yellowish  or  creamy  tint,  and 
the  object  of  this  operation  is  to  destroy  the  traces  of 
colouring  matter  from  which  it  arises.  The  pieces  are 
passed  through  a  very  dilute  solution  of  chloride  of  lime 
or  "  bleaching-powder,"  in  a  "  chemicking  "  machine, 
which  is  exactly  similar  to  that  employed  for  washing, 
and  are  then  allowed,  while  still  moist,  to  remain  in  pile 
and  exposed  to  the  air  for  a  few  hours  or  over-night.  The 
bleaching  action,  which  must  be  considered  as  one  of 
oxidation,  takes  place  largely  during  this  exposure,  hypo- 
chlorous  acid  being  then  liberated  by  the  action  of  the 
carbonic  acid  of  the  air. 

It  is  essential  that  the  bleaching-powder  solution  should 
not  be  too  strong,  otherwise  the  cloth  may  be  tendered 
or  be  partially  changed  into  oxycellulose,  and  thereby 
be  apt  to  attract  certain  colouring  matters  in  the  dye-bath, 
or  to  contract  brown  stains  during  subsequent  steaming 
processes.  For  the  same  reason  the  solution  of  bleaching- 
powder  should  be  entirely  free  from  undissolved  particles. 

The  bleaching  power  of  the  liquor  should  be  main- 
tained as  constant  as  possible  by  having  a  continual  flow 
of  fresh  bleaching-powder  solution  into  the  machine,  and 
by  occasionally  testing  how  much  of  the  liquor  is  required 
to  decolorise  a  specially  prepared  standard  solution  of 
arsenate  of  soda,  tinted  with  indigo  extract  or  cochineal 
decoction. 

6.  White-sour. — This  operation  does  not  differ  from 
the  lime-sour  already  described.  Its  object  is  to  com- 
plete the  bleaching  action  by  decomposing  any  "  chloride 
of  lime  "  still  in  the  cloth,  also  to  remove  the  lime,  the 
oxidised  colouring  matter,  and  any  traces  of  iron  present. 
The  cloth  usually  remains  saturated  with  the  acid  a  few 
hours. 

7.  The  final  washing  must  be  as  thorough  as  possible, 
and  is  usually  performed  by  the  square  beater  machine. 


84 


TEXTILE  FABRICS. 


After  squeezing,  the  cloth  is  again  opened  out  to  the  full 
width,  previous  to  drying.  This  is  effected  by  allowing 
a  lengthened  portion  of  the  chain  of  cloth  to  hang  loosely 
and  horizontally,  and  in  this  position  to  pass  between  a 
pair  of  rapidly  revolving  double-armed  scutchers,  which 
shake  out  the  twists  from  the  horizontal  length  of  cloth. 
The  two  arms  of  the  scutcher  merely  loosen  the  twists, 
and  whilst  in  this  loose  condition  the  cloth  passes,  over  and 
under  respectively,  two  spiral  rollers.  The  spiral  works 
outwards  from  the  centre  on  each  roller,  so  that  the 
piece  is  subjected  towards  the  selvages  to  a  smoothing-out 
action.  This  is  generally  sufficient  to  effectually  open  out 
the  cloth,  but  for  heavy  goods  one  type  of  Mycock  scutcher 
is  provided  with  spirally  wound  beater  blades  in  addi- 
tion to  the  spiral  rollers.  By  means  of  a  sun  and  planet 
motion,  the  spirally-wound  blades  receive  a  rapid  rotation 
in  addition  to  the  motion  of  the  scutcher  arms  which 
carry  them.  In  this  machine  there  is  also  a  governing 
action,  the  piece  passing  under  tension  through  swivelling 
bars.  When  the  piece  leaves  the  centre,  the  overlapping 
side  swivels  the  bars  at  its  own  side,  and  in  that  manner 
changes  the  angle  at  which  it  is  delivered  to  the  rolls. 
That  angle  throws  it  nearer  the  centre  of  the  rolls,  and 
so  has  a  contrary  effect,  which  nullifies  the  first  deviation. 
Instead  of  the  governor  bars  being  swivelled  at  their 
centre,  in  a  more  modern  Mycock  machine  a  parallel 
motion  is  provided  at  each  end  of  the  bars,  which  prevents 
the  swinging  action,  to  which  centre  swivels  are  subject, 
being  set  up. 

At  this  stage  the  piece  can  often  be  dried,  and  is  ready 
for  that  operation  if  it  is  wide  enough.  Nowadays, 
however,  manufacturers  so  cut  their  prices  that  with  plain 
goods  they  can  afford  no  more  width  than  necessary  in  tne 
piece,  and  the  result  is  that  not  enough  is  allowed  for 
shrinkage.  The  finisher  must  make  up  for  this,  so  that 
between  the  scutcher  and  the  drying  machine  an  expan- 
der is  frequently  employed.  For  light  stretches  spirally- 
wound  rollers  are  sufficient  if  set  closely  to  the  nip 
of  the  rolls  of  the  drying  machine,  while  two  conical 
rollers  and  other  devices  are  sometimes  used.  To  get  a 
powerful  stretch,  however,  and  bring  the  cloth  out  to 
near  loom  width,  bar  expanders  are  necessary. 


COTTON  BLEACHING. 


85 


The  most  modern  of  these  is  shown  in  Fig.  25,  this  being 
the  Mycock  five-bar  expander.  As  a  rule,  a  three-bar 
expander  is  all  that  is  necessary,  and  the  five-bar  is  only 


used  in  the  water  mangle  so  as  to  take  the  stretched  piece 
right  up  to  the  nip  of  the  rolls.  This  latter  is  done  by 
making  the  two  extra  bars  take  the  curve  of  a  circle  of 
greater  diameter,  and  so  get  nearer  a  straight  line.  These 


86 


TEXTILE  FABRICS. 


bars  are  made  up  of  small  shell  sections,  mounted  on  a 
central  core  independently  of  each  other,  but  fitting  into 
each  other  so  that  they  all  rotate  together  with  the  cloth. 
The  outer  circumference  of  the  sections  are  fluted  so  as 
to  better  grip  the  cloth,  but,  being  mounted  on  a  curved 
bar,  must  open  out  on  the  convex  side  to  meet  the  differ- 
ence between  the  inner  and  outer  sides  of  the  curve.  In 
thus  opening  out,  the  cloth  is  taken  with  them  and  the 
necessary  expansion  in  width  obtained,  as  can  be  seen  by 
the  course  of  the  cloth  in  Fig.  25.  Regulation  of  width  is 
made  possible  by  altering  the  position  of  the  middle  bar  in 
the  three-bar  expander  and  the  second  and  fourth  bars 
in  the  five-bar  expander.  These  regulating  bars  can  be 
raised  or  lowered  at  will  by  the  chains  and  sprocket  wheels 
shown  and  screw  gearing  not  shown,  their  height  deter- 
mining the  amount  of  bearing  surface  which  the  cloth  has 
on  the  bars,  and  therefore  the  amount  of  expansion  it 
receives. 

The  average  length  of  time  required  for  the  madder- 
bleach  is  4-5  days. 

Turkey -red-bleach  is  used  when  calico  is  intended  to 
be  dyed  Turkey-red,  as  then  it  is  not  necessary  to  give  it 
the  madder-bleach,  since  no  white  ground  has  to  be  pre- 
served. Certain  modifications,  too,  are  introduced ;  it  is 
found,  for  example,  that  singeing,  and  the  application 
of  bleaching-powder  which  causes  the  formation  of  oxy- 
cellulose,  interfere  with  the  production  of  the  most  brilli- 
ant colour.  The  apparatus  employed  being  similar  to  that 
already  described,  it  is  only  necessary  to  give  the  follow- 
ing summary  of  the  operations  usually  carried  out  : — 

1.  Wash. 

2.  Boil  in  water  for  two  hours  and  wash. 

3.  Ley-boils  :  1st,  90  litres  (20  gals.)  caustic  soda,  70°  Tw.  (Sp.  Gr. 

1  35),  boil  ten  hours  and  wash. 
2nd,  70  litres  (15  gals.),  ditto,  ditto. 

4.  Sour  :  Sulphuric  acid,  2°  Tw.  (Sp.  Gr.  l'Ol),  steep  two  hours. 

5.  Wash  well  and  dry. 

The  above  quantities  of  materials  are  intended  for 
2,000  kg.  —  2  tons  cloth,  with  low-pressure  kier. 

In  market-bleach  the  essential  difference  consists  in  the 
absence  of  the  boiling  with  resin-soap,  and  the  introduc- 
tion of  tinting  the  cloth  with  some  blue  colouring  matter 


COTTON  BLEACHING. 


87 


previous  to  drying.  With  many  bleachers,  the  operation 
of  chemicking  comes  between  the  two  ley-boils,  and  not 
after  them,  as  is  usually  the  case. 

Bleaching  by  Electrolysis. — The  production  of  bleach- 
ing liquor  by  electrolysis  is  yet  somewhat  rare  in  this 
country,  but  has  already  been  largely  adopted  on  the 
Continent.  It  offers  distinct  advantages  where  electric 
current  is  cheap.  A  common  salt  solution  can  be  split  up 
by  the  electric  current,  and  chlorine  gas  given  off  at  the 
anode  of  a  cell  whilst  metallic  sodium  is  deposited  at  the 
cathode.  The  sodium  is  reacted  upon  by  the  solution  and 
dissolved,  so  that  sodium  hydrate  in  solution  is  obtained 
and  hydrogen  gas  liberated.  At  the  anode  the  evolved 
chloride  combines  with  this  sodium  hydrate,  providing 
the  liquor  is  kept  in  circulation  and  the  poles  are  not 
too  far  apart,  and  in  this  manner  is  produced  liquid 
sodium  hypochloride. 

In  the  Oettel  electrolyser  a  long  cell  is  subdivided  into 
numerous  cells  by  carbon,  this  latter  material  being  used 
for  both  anode  and  cathode.  The  cells  have  a  common 
opening  at  the  bottom,  so  that  when  the  electric  current 
is  turned  on  the  liquid  effervesces,  and  flows  over  the  top 
into  pipes  which  lead  it  into  the  lower  and  open  part  of 
the  large  cell.  In  this  way  the  necessary  circulation  is 
kept  up  without  the  aid  of  pumps.  In  the  Mather  and 
Piatt  electrolyser  platinum  alloy  is  used  for  the  electrodes, 
and  in  this  case  a  pump  is  necessary  to  circulate  the 
liquid.  A  very  useful  feature  of  the  latter  apparatus  is 
the  detachable  mounting  of  alternate  electrodes,  which 
makes  cleaning  both  easy  and  possible  during  working. 


88 


CHAPTER  VI. 

LINEN  BLEACHING. 

The  bleaching  of  linen  is  more  or  less  similar  to  that  of 
cotton,  although  it  is  decidedly  more  tedious,  owing  to  the 
larger  proportion  of  natural  impurities  present  in  the  flax 
fibre,  and  the  greater  difficulty  of  removing  or  discolor- 
ising  them.  These  impurities  consist  principally  of  the 
brown  insoluble  pectic  acid,  which  remains  on  the  fibre 
after  the  retting  process,  to  the  extent  of  25-30  %.  Linen 
is  bleached  in  the  form  of  yarn,  thread,  and  cloth. 

Bleaching  Linen  Yarn  and  Thread. — Linen  yarn  is 
frequently  only  partially  bleached,  and  one  distinguishes 
yarns  which  are  "  half  white  "  (cream),  "  three-quarters 
white,"  and  "  full  white." 

The  following  is  an  outline  of  the  general  method  of 
bleaching  linen  yarn  as  at  present  adopted  in  Ireland. 
The  percentages  relate  to  the  weight  of  yarn  under  treat- 
ment : — 

1.  Boil:  10%'  soda-ash,  boil  3-4  hours;  wash  and  squeeze. 

2.  Reel :  bleaching  powder  solution,  \°  Tw.  ;  reel  1  hour ;  wash. 

3.  Sour:  sulphuric  acid,  1°  Tw.,  steep  1  hour;  wash. 

4.  Scald:  2-5%  soda-ash,  boil  1  hour;  wash. 

5.  Reel  :  as  No.  2  ;  wash. 

6.  Sour :  as  No.  3  ;  wash  well  and  dry. 

At  this  stage  the  yarn  should  be  "  half  white." 

If  it  is  required  "  three-quarters  white/7  the  drying 
is  omitted,  and  operations  4,  5,  and  6  are  repeated  with  the 
following  slight  modifications  :  (a)  after  the  "  scald  "  the 
yarn  is  u  grassed,"  i.e.  spread  on  the  grass  in  a  field  for 
about  a  week ;  (b)  instead  of  reeling  the  yarn  in  the  solu- 
tion of  bleaching-powder,  it  is  simply  steeped  in  it  for 
10-12  hours,  an  operation  which  is  analogous  to  the  chem- 
icking  of  cotton  yarn,  and  usually  called  the  "  dip." 

If  the  yarns  should  be  "  full  white  "  the  same  opera- 
tions are  again  repeated  once  or  twice,  the  duration  of 
grassing  being   varied   according   to   necessity   and  the 


LINEN  BLEACHING. 


Si) 


weather.  In  each  succeeding  operation  the  concentration 
of  the  solutions  employed  is  diminished. 

The  operation  of  boiling  takes  place  in  ordinary  open 
or  low-pressure  kiers,  while  those  of  dipping,  souring, 
and  washing  are  best  performed  in  the  apparatus  illus- 
trated in  Fig.  20,  page  72.  In  many  establishments,  how- 
ever, the  dipping  and  souring  are  effected  by  simply 
steeping  the  yarn  in  stone  tanks  filled  with  the  necessary 
liquids,  but  owing  to  the  absence  of  all  circulation  of  the 
latter,  this  plan  cannot  be  so  effective.  The  washing  is 
frequently  done  in  wash-stocks,  or  dash-wheels,  but  this 
also  is  not  good,  because  it  tends  to  make  the  yarn  rough. 

The  mode  of  applying  the  bleaching-powder  solution 
in  the  earlier  stages  by  "  reeling,"  is  peculiar  to  linen 
yarn  bleaching.  Its  primary  object  has  probably  been  to 
ensure  regularity  of  bleach,  but  since  the  carbonic  acid  of 
the  air  decomposes  the  calcium  hypochlorite  more  readily 
by  this  means,  and  liberates  hypochlorous  acid  within  the 
fibre,  as  it  were,  the  bleaching  must  be  more  thorough  and 
greatly  accelerated. 

The  reeling  machine  consists  of  a  large  shallow  stone 
cistern  holding  the  solution  of  bleaching-powder,  and  pro- 
vided with  a  movable  framework  supporting  a  number  of 
reels.  On  these  are  suspended  the  hanks  of  yarn  in  such 
a  manner  that  only  their  lower  ends  dip  into  the  liquid. 
Each  single  reel  can  be  readily  detached  if  necessary,  or, 
by  means  of  a  hydraulic  lift,  the  whole  framework  with 
reels  and  yarn  can  be  raised  and  withdrawn  from  the 
liquid,  and  at  once  transferred  to  another  and  similar 
cistern  for  the  purpose  of  washing,  etc.  Some  bleachers 
use  this  machine  for  scalding. 

It  is  said  that  better  results  are  obtained  if  the  cal- 
cium hypochlorite  is  replaced  by  the  corresponding  mag- 
nesium compound.  Probably  the  best  agent  to  use  would 
be  sodium  hypochlorite,  since  there  would  then  be  no 
formation  on  the  fibre  of  any  insoluble  carbonate,  and 
washing  might  largely  replace  the  souring,  in  which  case 
weaker  acids  even  than  those  mentioned  could  be  used. 
Since  calcium  chloride  is  more  soluble  than  the  sulphate, 
it  seems  likely  that  where  calcium  hypochlorite  is  used, 
hydrochloric  acid  would  be  better  as  a  souring  agent  than 
sulphuric  acid. 


TEXTILE  FABRICS. 


Bleaching  Linen  Cloth. — The  following  is  an  outline 
of  a  modern  Irish  process  for  1,500  kg.  =  1*47  tons  brown 
linen  (lawns,  handkerchiefs,  etc.),  with  low-pressure 
kiers  : — 

1.  Lime-boil:   125  kg.  rzr  275*57  lb.  lime,  boil  14  hours;  wash 

40  minutes  in  stocks. 

2.  Sour:  hydiochloric  acid,  2J°  Tw.  (Sp.  Gr.  1-0125),  steep  2-6 

hours;  wash  40  minutes  in  stocks  ;  "  turn  hank,"  and  wash  30 
minutes  in  stocks. 

3.  Ley-boils:  1st,  30  kg.  =6613  lb.  caustic  soda  (solid),  30  kg. 

—  66*13  lb  reisin,  previously  boiled  and  dissolved  together  in 
water  :  2,000  litres  z=  440*19  gals,  water  ;  boil  8-10  hours  ;  run 
off  liquor,  and  add — 
2nd,  15  kg.  ~  33*06  lb.  caustic  soda  (solid),  dissolved;  2,000 
litres  =  440*19  gals,  water,  boil  6-7  hours  ;  wash  40  minutes  in 
stocks. 

4.  Expose  in  field  2-7  days,  according  to  the  weather. 

5  Chemick  :  chloride  of  lime  solution,  J°  Tw.  (Sp.  Gr.  0*0025),  steep 
4-6  hours;  wash  40  minutes  in  stocks. 

6.  Sour:  sulphuric  acid,  1°  Tw.  (Sp.  Gr  0*005),  steep  2-3  hours; 

wash  40  minutes  in  stocks. 

7.  Sc.tld:    8-13   kg.  ==  17*63   to  28  65   lb.   caustic  soda  (solid) 

dissolved,  2,000  litres  water,  boil  4-5  hours ;  wash  40  minutes 
in  stocks. 

8.  Expose  in  field,  2  4  days. 

9.  Chemick:  chloride  of  lime  solution,  £°  Tw.  (Sp.  Gr.  0*00125), 

steep  3-5  hours  ;  Avash  40  minutes  in  stocks. 

The  goods  are  examined  at  this  stage ;  those  which 
are  sufficiently  white  are  soured  and  washed,  and  those 
which  are  not  are  further  treated  as  follows  :  — 

10.  Rub  with  rubbing  boards  and  a  strong  solution  of  soft  foap. 

11.  Expose  in  field  2-4  days. 

12.  Chemick:  chloride  of 'lime  solution,  i°  Tw.  (Sp.  Gr.  0*0006), 
steep  2-4  hours  :  wa^h  40  minutes  in  stocks. 

13.  Sour:  sulphuric  acid,  1°  Tw.  (Sp.  Gr.  0*005),  steep  2-3  hours; 
wash  40  minutes  in  stocks. 

When  the  cloth  (cream  linen)  is  made  of  yarn  already 
partially  bleached,  a  less  severe  process  is  required,  e.g. 
less  lime  is  used  in  the  lime-boil ;  only  one  ley-boil  is 
given,  and  that  with  resin-soap  instead  of  caustic  soda; 
weaker  chloride  of  lime  solutions  are  used ;  the  scald  is 
effected  with  soda-ash  solution ;  and  operations  8  and  9 
are  omitted. 

What  is  known  as  "  brown  holland  ;;  is  a  plain  linen 
cloth  which  has  had  little  or  no  bleaching,  but  only  a 


LINEN  BLEACHING. 


91 


short  boiling  in  water,  or  in  weak  soda-ash  solution,  fol- 
lowed by  a  weak  souring.  It  possesses,  therefore,  more  or 
less  the  natural  colour  of  the  retted  flax  fibre. 

The  washing  is  usually  effected  in  the  wash-stocks,  but 
sometimes,  and  with  advantage,  too,  in  so-called  slack- 
washing  machines,  trie  washing  trough  being  divided  by 
wooden  spars  into  several  compartments,  each  capable  of 
holding  several  yards  of  slack  cloth  between  each  nip. 

The  "  rubbing  referred  to  is  a  characteristic  feature 
in  linen  cloth  bleaching,  and  has  for  its  object  the  removal 
of  small  particles  of  brown  matter  called  "  sprits."  It 
is  effected  by  a  special  machine,  which  consists  essentially 
of  a  pair  of  heavy  corrugated  boards  resting  on  each 
other ;  the  upper  one  is  moved  lengthwise  to  and  fro, 
while  the  pieces  are  led  laterally  between  them. 

The  exposing  of  the  goods  in  a  field  to  the  influences  of 
air,  moisture,  and  light,  or  "  grassing/'  as  it  is  technically 
termed,  is  still  very  generally  adopted  in  order  to  avoid 
steeping  too  frequently  in  solutions  of  bleaching-powder, 
and  thus  to  preserve  as  much  as  possible  the  strength  of 
the  fibre. 

"  Turn-hanking  ';  consists  in  loosening  the  entangled 
pieces  and  refolding  them,  so  that  every  part  may  be  ex- 
posed to  the  action  of  the  hammers  of  the  wash-stocks ; 
the  operation  is  introduced  as  often  as  required  at  vari- 
ous stages  of  the  bleaching  process,  but  especially  after 
washing  in  the  stocks. 

Chemistry  of  Linen  Bleaching. — During  the  several 
boilings  with  lime,  soda-ash,  caustic  soda,  or  resin-soap, 
the  insoluble  brown-coloured  pectic  acid  of  the  retted  fibre 
is  decomposed,  and  changed  into  metapectic  acid,  which 
combines  with  the  alkali  to  form  a  soluble  compound. 
According  to  the  origin  of  the  flax,  the  loss  which  it 
thus  sustains  may  vary  from  15-36  %. 

By  the  application  of  bleaching-powder  alone,  the 
brown  pectic  matters  are  bleached  only  with  great  diffi- 
culty, and  even  then  only  by  using  "  chloride  of  lime 
solutions  of  such  concentration  that  the  fibre  itself  is  apt 
to  be  attacked.  After  a  number  of  successive  boilings 
with  alkali,  however,  the  goods  retain  merely  a  pale  grey 
colour,  which  is  readily  bleached  by  comparatively  weak 
solutions  without  injury  to  the  fibre. 


92 


TEXTILE  FABRICS. 


The  rational  mode  of  bleaching  linen  would  seem  to  be, 
therefore,  to  defer  the  application  of  the  bleaching-powder 
until  the  pectic  matters  have  been  almost  or  entirely 
removed  by  lime  and  alkaline  boilings,  although,  in 
practice,  this  plan  is  never  strictly  adhered  to.  A  single 
ley-boil  scarcely  removes  more  than  10  %  of  the  pectic 
matters,  and  since  their  presence  in  such  large  proportion 
prevents  the  solutions  of  bleaching-powder  from  decoloris- 
ing the  whole  of  the  grey  matter  at  one  operation,  the 
usual  plan  is  to  alternate  the  alkaline  boilings  with  dilute 
chloride  of  lime  treatments ;  the  more  so  because  it  is 
considered  that  a  slight  oxidation  of  the  pectic  matters 
facilitates  their  removal  by  the  alkaline  boilings,  and 
that  the  latter  predispose  them  to  oxidation. 

Well-bleached  linen  ought  not  to  be  discoloured  when 
steeped  in  a  dilute  solution  of  ammonia ;  if  by  this  treat- 
ment the  linen  acquires  a  yellow  tint,  it  is  a  sign  that  the 
pectic  matters  have  not  been  entirely  removed. 

The  usual  period  required  for  bleaching  brown  linen 
varies  from  3-6  weeks. 


93 


CHAPTER  VII. 

MERCERISING. 

The  Principles  of  Mercerisation. — If  cotton  or  linen,  in 
either  the  raw  or  manufactured  state,  is  subjected  to  a 
cold  solution  of  caustic  soda  of  a  density  of  about  25°  Be., 
it  instantly  shrinks,  and  at  the  same  time  becomes  stronger 
and  capable  of  more  easily  absorbing  dyestuffs  than  in 
its  original  state.  If,  however,  the  material  is  treated 
whilst  under  tension  so  as  to  prevent  shrinkage,  or  if 
whilst  still  wet  i,t  is  stretched  back  to  as  near  its  original 
dimensions  as  possible,  the  fibres  swell  and  become  trans- 
lucent, as  when  treated  without  tension,  but  at  the  same 
time  there  is  a  drawing  action  amongst  them  which  ulti- 
mately leaves  them  with  a  gloss  not  unlike  that  of  the 
silk  fibre. 

Experience  has  clearly  shown  that  solutions  of  soda-lye 
stronger  than  25°  Be.  do  not  produce  any  better  effect,  and 
that  also  it  is  useless  prolonging  the  immersion,  for  the  full 
possible  amount  of  action  takes  place  in  about  a  minute. 
With  weaker  solutions  than  the  above  a  corresponding 
weaker  lustre  is  obtained,  while  little  effect  is  possible 
with  lyes  weaker  than  about  20°  Be.  Heating  the  lye  has 
no  better  effect  unless  the  solution  is  made  correspondingly 
strong,  about  50°  C.  being  the  best  working  temperature. 
The  mercerising  action  is  discernible  on  all  classes  of 
cotton  and  linen,  but  it  is  not  found  advantageous  to  work 
any  but  the  long-fibred  cottons,  as  with  the  short-fibred 
classes  the  result  is  insignificant. 

Tensioning  Devices. — It  is  extremely  difficult  to  pro- 
perly mercerise  raw  material,  as  there  is  no  reliable 
method  of  gripping  the  fibres  and  keeping  them  under 
tension.  The  best  way  is  to  lay  the  cotton  or  linen  between 
two  sheets  of  fine  mesh  wire  fabrics,  and  whilst  held  be- 
tween these  to  treat  with  soda  lye  and  wash  off. 

Yarn  is  the  most  satisfactory  state  in  which  to  mercerise 


94 


TEXTILE  FAB  RIG 8. 


vegetable  fibres,  especially  when  it  is  in  hank  form.  The 
hanks  are  placed  over  two  rollers,  and  these  can  be  forced 
apart  by  either  levers  or  by  screws.  Frames  carrying 
these  rollers  can  be  filled  with  hanks  and  dropped  into 
the  different  vats:  first,  one  containing  soda  lye;  second 
one  containing  clean  water  for  washing-off  purposes; 
third,  a  souring  tank  containing  a  weak  solution  of  sul- 
phuric acid  to  neutralise  any  remaining  caustic  soda;  and 
fourth,  another  wash  to  clear  away  the  acid. 

Not  only  are  there  various  frames  of  this  description 
on  the  market,  but  there  are  several  good  machines  which 
automatically  perform  the  operations.  These  are  a  great 
advantage,  for  the  process  can  be  carried  out  very  rapidlv. 
whilst  special  gloves  need  not  be  worn,  although  it  is 
necessary  when  the  operator  has  to  handle  the  yarn 
before  the  lye  is  washed  out. 

Yarn  can  also  be  mercerised  whilst  in  warp  form.  The 
warp  is  passed  through  what  is  practically  a  warp  dyeing 
machine,  but  the  warp  is  kept  tight  between  the  sets  of 
rollers,  so  as  to  prevent  shrinkage. 

The  mercerisation  of  piece  goods  is  usually  carried  out 
by  treating  the  woods  with  the  lye  and  then  stretching  them 
back  to  width  on  the  tentering  machine.  In  other  cases 
the  stretching  is  done  in  the  crabbing  machine,  but  it  will 
be  readily  seen  that  the  former  will  only  stretch  the  weft 
threads  properly,  whilst  the  latter  only  influences  the 
warp.  There  are  also  special  tentering  machines  made  in 
which  the  cloth  can  be  taken  through  the  several  baths 
and  prevented  from  shrinking  during  the  process,  instead 
of  the  after-stretching  above-mentioned. 

Fancy  Effects  Obtained  by  Mercerisation. — Fancy 
effects  can  be  obtained  by  mercerisation  by  using  either 
the  lustring  properties  of  the  process  or  the  shrinkage 
which  is  present.  By  the  former,  invisible  effects  may  be 
obtained  by  printing  soda  lye  on  a  fabric  under  tension, 
when  the  figures  come  out  in  the  same  shade  as  the  rest 
of  the  piece,  but  brighter.  This  applies  only  to  white 
goods,  for  the  parts  so  printed  would  show  a  darker 
shade  in  a  dyed  piece. 

Effects  may  be  also  obtained  of  a  crepon  nature  by 
printing  portions  of  a  fabric  and  allowing  it  to  shrink, 
whilst  the  untreated  parts  retain  their  usual  dimensions. 


MERCERISING. 


95 


Lustring  Without  Tension. — Attempts  have  been  made 
to  obtain  the  lustre  which  follows  treatment  in  soda  lye 
under  tension  without  the  accompanying  tension.  So  far 
the  methods  attempted  have  consisted  of  adding  some- 
thing to  the  lye,  but  although  there  has  been  a  small 
measure  of  success  it  is  usually  found  that  the  lustre 
suffers. 

The  glycerine  process  is  so  far  the  most  successful,  one 
part  of  glycerine  mixed  with  two  parts  of  soda  lye  50°  Be., 
practically  preventing  shrinking  and  giving  a  lustre  which 
almost  comes  up  to  properly  treated  goods. 

The  other  methods  already  tried  consist  of  adding 
alcohol,  gelatine,  waste  silk,  dissolved  wool,  glucose, 
sodium  silicate,  hydrocarbons,  etc.,  to  the  caustic  soda. 


96 


CHAPTER  VIII. 

WOOL    SCOURING    AND  BLEACHING. 

Object  of  Scouring  Wool. — The  u  scouring  "  of  wool  has 
for  its  object  the  complete  removal  of  all  those  natural 
and  artificial  impurities  (yolk,  dirt,  oil,  etc.)  which  would 
otherwise  act  injuriously  during  the  processes  of  weaving 
or  dyeing. 

The  paramount  importance  of  having  woollen  material 
thoroughly  well  cleansed  or  scoured  previous  to  dyeing, 
cannot  be  too  much  insisted  upon.  If  the  operation  be 
omitted,  or  be  improperly  or  incompletely  performed, 
each  fibre  remains  varnished,  as  it  were,  with  a  thin 
layer  of  fatty  matter,  whicn  resists  to  a  greater  or  less 
degree  the  absorption  and  fixing  of  mordant  or  colour- 
ing matter.  The  final  result  is  that  the  material  is  badly 
or  unevenly  dyed,  and  appears  "  flecked, "  "  stripey,"  etc., 
or  since  the  colouring  matter  can  only  be  superficially  de- 
posited, it  is  readily  removed  by  the  subsequent  operations 
of  washing,  milling,  etc. 

It  has  already  been  mentioned,  when  considering  the 
wool  fibre,  that  raw-wool  is  impregnated  or  encrusted 
with  yolk,  consisting  essentially  of  certain  fatty  matters, 
free  fatty  acids,  etc.  Woollen  yarn  and  cloth  always  con- 
tain oil  (olive  oil,  oleic  acid,  etc.)  to  the  extent  of  about 
10-15  %,  which  has  been  sprinkled  on  the  wool  for  the 
purpose  of  facilitating  the  spinning  process. 

It  would  be  a  great  advantage,  however,  if  manufac- 
turers would  more  frequently  use  neutralised  sulphated 
castor-oil  soap  solutions  instead  of  oil,  for  this  purpose. 
Cloth  which  required  milling  after  dyeing  (e.g.  mixtures, 
tweeds,  etc.),  or  previous  to  dyeing,  would  then  need  no 
scouring  with  alkali,  but  merely  a  simple  washing  in  soft 
water.  This  plan  has  been  adopted  with  success  in  Bel- 
gium. 

The  method  of  removing  yolk,  oil,  etc.,  from  wool, 


WOOL  SCOURING  AND  BLEACHING. 


97 


which  first  suggests  itself,  is  that  of  saponifying  or  emul- 
sifying them  by  means  of  weak  alkaline  solutions,  and 
such,  indeed,  are  the  agents  most  largely  employed  for  the 
purpose  of  wool  scouring. 

The  choice  of  the  most  suitable  alkaline  scouring  agent 
and  the  best  temperature  to  be  employed  depend  upon 
the  quality  and  origin  of  the  wool. 

In  modern  times  other  agents  of  a  volatile  nature, 
and  capable  of  dissolving  fatty  substances,  have  been  pro- 
posed and  to  some  extent  employed — e.g.  fusel  oil,  ether, 
light  petroleum  oil,  carbon  disulphide,  etc. — and  it  is  by 
no  means  improbable  that  some  member  of  this  class  will 
form  the  wool-cleansing  agent  of  the  future.  It  must  be 
remembered,  however,  that  these  volatile  liquids  are  es- 
sentially solvents  for  fatty  matters,  and  not  for  alkaline 
oleates.  A  washing  in  water  would  therefore  always  have 
to  take  place  in  addition. 

Scouring  Agents. — Lant  or  stale  urine  is  the  detergent 
which  has  been  employed  for  wool-scouring  from  the 
earliest  times,  and  it  is  effective  because  of  the  ammonium 
carbonate  it  contains.  Though  still  used,  this  agent  has 
been  largely  supplanted  by  others,  such  as  ammonia, 
sodium  carbonate,  soap,  etc. 

Stale  urine,  used  in  the  proportion  of  1  measure  to 
about  5  of  water,  gives  excellent  results  in  most  cases. 
It  leaves  the  wool  clean  and  with  its  normal  physical 
properties  of  softness,  elasticity,  etc.,  unimpaired,  its  dis- 
agreeable odour  being  its  main  defect.  Ammonium  car- 
bonate is  the  most  rational  substitute  for  "  lant,77  and 
represents,  perhaps,  one  of  the  best  alkaline  detergents, 
especially  if  used  along  with  soap  ;  but  it  is  still  too  ex- 
pensive for  general  use.  As  a  mild  scouring  agent  for  the 
better  classes  of  wool,  potash  or  soda  soap  is  largely  em- 
ployed. Satisfactory  results  are  obtained  with  these  if 
the  soap  is  of  good  quality,  and  free  from  excess  of  caustic 
or  carbonated  alkali.  Other  things  being  equal,  the  most 
soluble  soaps  are  to  be  preferred,  such  as  potash  soaps, 
or  soda  soaps  made  from  oleic  acid.  An  average  soap 
solution  may  contain  30-50  g.  of  soap  per  litre  of 
water  (4*8-8  oz.  per  gal.).  An  addition  of  ammonia 
to  the  soap  solution  is  frequently  made  for  the  purpose  of 
increasing  its  detergent  properties.    An  important  con- 

G 


<;»8 


TEXTILE  FABRICS. 


sideration  to  be  remembered  when  using  soap  is,  that  the 
water  should  be  as  free  as  possible  from  lime  and  magnesia 
to  avoid  the  formation  of  lime  and  magnesia  soaps. 

The  scouring  agent  most  largely  employed,  either  alone 
or  mixed  with  soap,  is  sodium  carbonate,  of  which  excel- 
lent qualities  (Solvay  soda,  "  Crystal  carbonate/'  etc.)  are 
now  to  be  had.  When  used  with  judgment  and  care,  it 
leaves  the  wool  but  little  affected,  and,  being  inexpensive, 
it  is  well  adapted  for  wools  of  medium  and  low  quality. 
The  injurious  effects  of  using  a  calcareous  or  magnesian 
water  are  less  marked  with  this  agent  than  with  soap, 
since  the  calcium  and  magnesium  carbonates  precipitated 
on  the  wool  are  of  powdery  nature  and  more  readily  re- 
moved. The  presence  of  caustic  soda  must  always  be 
rigidly  avoided.  The  concentration  of  the  soda  solution 
should  be  such  that  it  stands  at  l°-2°  Tw.  (Sp.  Gr.  1*005- 
T01),  or,  say,  10-20  g.  =  0'35-0'70  oz.  Na2CO310H2O  per 
litre.  It  may  be  stated,  as  a  general  rule,  that  the  best 
results  are  obtained  (i.e.  as  regards  feel  and  lustre  of 
wool)  by  using  the  solutions  of  alkaline  detergent  as 
dilute,  and  at  as  low  a  temperature  as  is  consistent  with 
the  complete  removal  of  all  impurities.  The  temperature 
may  vary  from  40°-55°  C. 

Other  substances  have  from  time  to  time  been  recom- 
mended as  useful  additions  to  the  scouring  bath,  e.g. 
common  salt,  ammonium  chloride,  decoction  of  soap  bark 
(Quillaya  saponaria),  olein,  resin  soap,  pigs'  manure 
(Seek),  etc.  Some  of  these  may  act  beneficially  in  certain 
cases,  but  as  a  rule  the  previously  mentioned  scouring 
agents  are  more  generally  useful.  Ammonium  chloride 
may  de-alkalise  soap,  or  if  used  along  with  sodium  car- 
bonate may  be  beneficial  because  of  the  ammonium  car- 
bonate produced.  Olein  and  resin-soap  probably  assist 
emulsification,  while  seek,  which  is  frequently  employed, 
is  effective  because  of  its  alkalinity. 

Patent  or  secret  scouring  substitutes  should  be  strictly 
avoided ;  they  are  either  worthless,  or,  if  useful,  they  can 
be  prepared  by  the  scourer  himself  more  economically. 
Secrets,  both  in  scouring  and  in  dyeing,  belong  rather 
to  the  past  than  to  the  present  age. 
Scouring  Loose-Wool  : — 

a.  Scouring  with  Alkaline  Solutions. — In  its  most  com- 


WOOL  SCOURING  AND  BLEACHING. 


<  9 


plete  form  the  scouring  (Fr.  lavage)  of  raw  or  greasy 
wool  should  consist  of  at  least  three  operations  : — 

1st.  Steeping  or  washing  with  water  (Fr.  desuintage). 

2nd.  Cleansing  or  scouring  proper  with  weak  alkaline 
solutions  (Fr.  degraissage). 

3rd.  Rinsing  or  final  washing  with  water  (Fr.  rincage). 

In  England  the  first  operation  is  omitted,  sometimes 
because  the  wool  has  been  already  more  or  less  completely 
washed  by  the  wool  grower,  in  order  to  lessen  the  expense 
of  transport,  but  more  frequently  because  the  opinion 
prevails  that  the  operation  is  unnecessary  and  only  en- 
tails additional  expense.  It  is  contended,  and  indeed  with 
some  degree  of  truth,  that  the  soluble  portion  of  the  yolk, 
owing  to  its  alkaline  nature,  renders  material  assistance 
in  the  scouring  bath. 

On  the  other  hand,  this  system  has  certain  defects. 
The  scouring  bath  becomes  more  readily  soiled  and  rapidly 
varies  in  composition,  so  that,  unless  it  be  frequently  re- 
newed, it  soon  scours  the  wool  insufficiently,  or  may  even 
stain  it  injuriously.  Under  ordinary  circumstances,  and 
scouring  with  sodium  carbonate  or  with  soda  soaps,  the 
yolk  is  entirely  lost. 

When  the  wool  contains  only  a  small  percentage  of 
yolk,  the  steeping  process  for  the  recovery  of  yolk-ash 
may  well  be  omitted,  but  its  adoption  in  the  case  of  wools 
rich  in  yolk  (as  those  from  Buenos  Ayres,  etc.)  is  certainly 
to  be  recommended  as  distinctly  advantageous.  In  Bel- 
gium and  France  it  is  largely  carried  on. 

Steeping. — To  be  effective  the  process  must  be  sys- 
tematic, the  water  should  be  heated  to  about  45°  C,  and 
the  wool  if  possible  agitated. 

In  practice,  the  last  point  is  not  attempted  on  economi- 
cal grounds,  and  the  wool  is  simply  steeped  in,  or  rather 
systematically  washed  with,  tepid  water  in  the  following 
manner  : — 

Four  or  five  large  iron  tanks  capable  of  being  heated 
by  steam  are  filled  with  the  raw  wool.  The  first  one  is 
then  filled  with  tepid  water  (45°  C),  and  the  wool  is 
allowed  to  steep  for  several  hours  until,  indeed,  no  further 
quantity  of  yolk  is  dissolved;  by  means  of  a  siphon, 
steam-injector,  pump,  or  other  means,  the  liquid  is  re- 
moved to  the  second  tank,  where  it  is  also  allowed  to 


100 


TEXTILE  FAB  BIGS. 


remain  (at  45°  C.)  until  it  again  ceases  to  dissolve  yolk;  it 
is  then  in  like  manner  removed  to  tanks  3  and  4,  until 
finally  it  becomes  perfectly  saturated  with  yolk,  and  is 
ready  for  being  evaporated  to  dryness,  calcined,  etc.,  to 
obtain  the  yolk-ash.  Simultaneously  with  what  has  just 
been  described,  fresh  water  (45°  C.)  is  made  to  circulate 
in  a  similar  manner  through  the  several  tanks,  until  at 
length  the  wool  in  tank  No.  1  is  entirely  deprived  of  the 
soluble  constituents  of  the  yolk ;  the  wool  being  now  ready 
for  the  scouring.  This  tank  is  emptied  and  refilled  with 
raw  wool.  So  soon  as  this  has  taken  place,  the  steeping 
water  is  made  to  circulate  through  the  tanks  in  the  order 
of  Nos.  2,  3,  4,  1,  so  that  the  saturated  yolk  solution  is 
now  drawn  off  from  the  newly-filled  No.  1  tank,  and  the 
wool  contained  in  No.  2  tank  is  exhausted,  which  is  then 
duly  emptied  and  refilled. 

By  the  above  explained  method  of  steeping  the  wool  in 
each  tank  becomes,  in  turn,  gradually  deprived  of  yolk, 
and  supposing  the  tanks  to  be  arranged  in  a  circle,  the 
points  at  which  the  fresh  water  is  introduced  and  the 
saturated  yolk  solution  withdrawn,  are  always  two  con- 
tiguous tanks,  and  move  gradually  round  the  circle.  The 
main  principle  of  the  process  is,  that  the  raw  greasy  wool 
is  always  first  washed  with  water  already  pretty  well 
saturated  with  yolk,  the  partly  extracted  wool  is  brought 
into  contact  with  weaker  yolk  solutions,  while  the  most 
thoroughly  exhausted  wool  is  washed  with  fresh  water. 

Figs.  26  and  27  represent  an  arrangement  of  washing 
tanks  designed  by  H.  Fischer  with  a  view  to  economise 
space  and  labour. 

a,  b,  c,  d,  represent  four  iron  tanks  suspended  be- 
tween two  large  wheels  F,  having  the  common  axis  e. 
One  of  the  wheels  is  provided  with  teeth,  which  work 
against  the  small  cog-wheel  of*  a  windlass,  the  arrange- 
ment being  such  that  the  whole  apparatus  can  be  readily 
turned  at  G  by  a  single  workman.  Each  tank  can  thus 
be  raised  in  turn  to  a  high  level  for  the  purpose  of  drain- 
ing the  wool  it  contains  and  running  the  liquid  into  the 
next  tank. 

The  following  numbers  giving  the  amount  of  dry  yolk 
in  yolk  solutions  of  different  degrees  of  concentration  are 
calculated  from  data  published  by  Havrez  :  — 


WOOL  SCOURING  AND  BLEACHING. 


102 


TEXTILE  FABRICS. 


According  to  M.  Chandelon,  1,000  kg.  -  2,204  lb.  of 
raw  wool  may  furnish  313  litres  -  6888  gal.  of  yolk  solu- 
tion of  Sp.  Gr.  1'25  (50°  Tw.),  having  a  value  of  15s.  6d., 
while  the  cost  of  extraction  does  not  exceed  2s.  6d. 

Fig.  28  represents  a  furnace  for  the  manufacture  of 
carbonate  of  potash  from  yolk,  devised  by  H.  Fischer. 

The  concentrated  yolk  solution  is  first  put  into  the 
tank  a  and  warmed  by  the  waste  heat  of  the  furnace. 
Sometimes  tank  a  is  situated  at  a  high  level,  and  the 
concentrated  yolk  solution  is  led  into  the  chimney,  where 
it  trickles  down  in  a  ziz-zag  course  across  overlapping 
steps  at  once  into  the  chamber  b.  The  flow  can  be  so 
regulated  that  the  level  of  the  liquid  in  b  is  constant. 
In  the  regular  course  of  work  the  liquid  is  run  from  the 


Fig*.  28. — Section  of  Furnace  for  Making-  Yolk-ash. 


tank  a  into  the  evaporating  chamber  b,  and  when  partly 
evaporated  here,  it  is  led  by  a  connecting  pipe  into  the 
calcining  chamber  c,  where  it  is  evaporated  down  to  a 
thick  syrupy  consistency.  Very  soon,  owing  to  the  organic 
matter  contained  in  it,  it  ignites,  and  the  fire  at  d 
can  be  much  moderated.  The  calcined  mass  in  c  is  worked 
about  with  a  rake  until  it  acquires  a  dirty  grey  colour, 
when  it  is  withdrawn  and  allowed  to  cool.  In  the  mean- 
time, the  liquid  in  b  has  been  evaporating,  and  fresh 
liquid  has  been  warmed  in  a.  When  properly  managed 
the  process  is  almost  continuous.  Care  must  be  taken 
in  admitting  new  liquid  from  b  into  the  red-hot  chamber  c, 
since  it  froths  up  very  considerably.  The  pipe  connect- 
ing b  and  c  is  so  arranged  that  it  can  be  readily  re- 
moved and  cleaned.  Comparatively  little  coal  is  required, 
since  it  is  largely  economise^  through  the  burning  of  the 
organic  .master  of;  the  yo{k  itself.    Itji^s,  been  found  in 


WOOL  SCOURING  AND  BLEACHING.  103 


practice  that  to  evaporate  12  kg.  =  26  44  lb.  of  water  in 
such  a  furnace  1  kg.  —  2*2  of  coal  is  required.  Yolk 
ash  is  recovered  in  Roubaix,  Antwerp,  Verviers,  Louvain, 
Brugge,  Hanover,  Dohren,  and  Bremen. 

Scouring  and  Washing. — In  small  establishments  the 
wool  is  thrown,  without  previous  steeping,  into  a  large 
tank  filled  with  the  scouring  liquid,  and  worked  about  by 
hand  for  a  short  time  with  poles.  It  is  then  lifted  out 
with  a  fork,  drained  on  a  wooden  screen,  and  well  washed 
several  times  in  a  cistern  having  a  perforated  false  bot- 
tom. When  soap  is  used,  the  excess  of  liquid  is  removed 
by  a  pair  of  squeezing  rollers  before  washing.  Obviously, 
by  this  method  the  wool  is  only  incompletely  or  irregu- 
larly scoured,  hence  in  large  and  well-equipped  establish- 
ments, after  "  steeping,"  it  is  passed  through  the  wool- 
scouring  machine. 

The  great  object  of  the  wool-scourer  should  be  to  main- 
tain the  composition  of  the  second  bath  as  constant  as 
possible,  or  at  least  not  to  allow  it  to  become  too  much 
soiled.  This  is  effected  partly  by  the  squeezing  rollers 
between  the  first  and  second  machines,  and  partly  by 
emptying  the  first  bath  the  moment  it  gets  charged  with 
fatty  matter,  transferring  to  it  the  slightly-soiled  liquor  of 
the  second  bath,  and  refilling  the  latter  with  fresh  scour- 
ing solution.  No  doubt  a  still  more  regular  and  complete 
scour  would  be  obtained  by  having  a  range  of  four  troughs 
instead  of  three.  If  the  amount  of  fatty  matter  remaining 
in  the  wool  after  scouring  exceeds  1%,  the  operation  must 
be  regarded  as  having  been  inefficiently  performed. 

Figs.  29  and  30  show,  respectively,  elevation  and  cross 
section  of  the  McNaught  wool-scouring  machine.  It  con- 
sists of  a  long  tank  a  containing  the  scouring  liquor,  part 
of  the  tank  being  partitioned  off  at  the  top  and  provided 
with  a  perforated  bottom  B.  The  wool  is  fed  into  the 
machine  by  the  lattice  c,  and,  after  passing  through  rolls, 
is  delivered  into  the  upper  compartment  of  the  tank  A, 
along  which  it  is  passed  by  forks  d.  These  forks  are  swung 
from  the  framework  shown,  and  by  means  of  cams  are 
operated  so  as  to  dip  into  the  liquor,  have  a  movement 
in  the  direction  in  which  the  wool  should  travel,  lift  from 
the  liquor,  and  have  a  backward  or  return  movement  in 
mid-air.    They  are  thus  continually  propelling  the  wool 


WOOL  SCOURING  AND  BLEACHING.  105 


in  one  direction,  whilst  the  return  current  of  liquor  can 
flow  along  the  upper  part  of  the  tank  a,  outside  the  com- 
partment containing  the  wool.  The  dirt  which  is  loosened 
from  the  wool  falls  through  the  perforated  bottom  plate  B 
and  slides  down  the  inclined  bottom  of  the  tank  a,  from 
whence  it  is  cleaned  at  intervals. 

On  reaching  the  right  end  of  the  drawing,  the  wool  is 
forked  up  an  incline  f,  and  then  falls  down  another  in- 
cline into  the  nip  of  the  squeeze  rolls  G,  which  pass  it  to 


Fig.  30. — McNaught's  Wool- scouring"  Machine — Cross  Section. 

the  lattice  H.  It  then  goes  forward  to  a  similar  machine, 
or  may  be  passed  forward  to  be  dried.  The  liquor  ejected 
by  the  squeeze  rolls  G  runs  through  perforations  in  the 
incline  and  down  to  the  small  tank  e  (Fig.  30),  from 
whence  it  is  pumped  back  again  into  the  main  tank  A. 

A  really  effective  scouring  arrangement  consists  of  at 
least  three  such  machines,  placed  in  line,  so  that  the  wool 
may  be  passed  automatically  from  one  to  the  other.  The 
operation  of  scouring  and  washing  thus  becomes  continu- 
ous, regular,  and  complete. 


106 


TEXTILE  FABRICS. 


The  first  machine  into  which  the  wool  is  introduced  con- 
tains more  or  less  soiled  scouring  liquor,  which  has 
already  been  used  in  the  second  trough;  the  latter  contains 
fresh  scouring  liquor,  and  the  third  a  continual  flow  of 
clean,  cold,  or  preferably  tepid,  water. 

Magma  Process. — The  waste  scouring  liquor  ought  to  be 
collected  in  stone-lined  pits,  and  there  neutralised  or  acidi- 
fied with  sulphuric  acid.  The  magma  of  fatty  matter 
which  rises  to  the  surface  is  collected,  drained  in  filter 
bags,  and  sold  to  oil  dealers.  If  soap  has  been  the  scour- 
ing agent  employed,  the  fatty  acids  thus  recovered  are  all 
the  more  valuable,  but  in  any  case  the  spent  scouring 
liquors  should  never  be  allowed  to  pollute  the  neighbour- 
ing stream. 

b.  Scouring  with  Volatile  Liquids. — This  is  more  advan- 
tageous than  the  alkaline  method,  because  it  deprives  the 
wool  more  completely  of  its  wool-fat,  and  the  injurious 
effect  of  the  alkalis  is  entirely  removed.  On  the  other 
hand,  the  method  is  more  costly,  and  by  the  use  of  some 
extracting  liquids  the  wool  may  certainly  be  modified. 

Some  consider  that  since  oil  must  be  added  to  the  wool 
before  spinning,  it  is  not  necessary  to  remove  the  whole  of 
the  natural  fatty  matters  from  raw  wool.  Whether  this 
view  be  correct  or  not  as  far  as  spinning  is  concerned, 
it  is  certainly  not  to  be  entertained  if  the  loose  wool  has 
to  be  dyed. 

Up  to  the  present  time,  wool  scouring  with  volatile 
liquids  has  not  met  with  general  acceptance,  partly  be- 
cause of  the  attendant  danger  if  not  employed  with  great 
care  and  with  suitable  appliances.  The  difficulties,  how- 
ever, are  not  insuperable,  and  have,  indeed,  been  more  or 
less  overcome  by  Da  Heyl,  Yan  Haecht,  and  others. 

One  method  is  that  of  T.  J.  Mullings.  The  wool  is 
placed  in  an  enclosed  centrifugal  machine,  and  submitted 
to  the  action  of  disulphide  of  carbon.  When  this  liquid 
is  saturated  with  yolk,  the  machine  is  set  in  motion  to 
remove  the  bulk  of  it,  the  remaining  portion  being  expelled 
by  admission  of  water.  The  wool  is  afterwards  washed 
with  water  in  the  usual  washing  machines.  The  novel 
feature  in  the  process  is  the  expulsion  of  the  carbon  disul- 
phide by  displacing  it  with  water,  by  which  means  the  wool 
does  not  acquire  the  yellow  tint  it  invariably  assumes  when 


WOOL  SCOURING  AND  BLEACHING.  107 


heat  is  employed  for  this  purpose.  The  mixture  of  carbon 
disulphide  and  water  is  collected  in  a  tank;  after  settling, 
the  former  is  drawn  off  from  below  and  recovered  for  sub- 
sequent use  by  distillation.  Experiments  are  said  to  have 
shown  that  wool  cleansed  in  this  way  is  stronger,  and 


Fig*.  31. — Yarn- stretching"  Machine. 


will  spin  finer  yarn,  and  with  less  waste,  than  if  scoured 
by  the  ordinary  method  with  soap,  and  this  is  done  at 
one-eighth  of  the  usual  cost. 

Yam  Scouring. — The  scouring  of  woollen  yarn  is  more 
readily  effected  than  that  of  raw  wool  if  the  oil  with 
which  it  has  been  impregnated  by  the  spinner  has  been 


108 


textile  Fabrics. 


of  good  quality  (e.g.  olive  oil).  It  has  always  been  con- 
sidered that  the  difficulty  is  increased  if  cheap  oils  have 
been  used  which  contained  an  appreciable  amount  of 
mineral  oil,  since  this,  being  a  hydro-carbon  and  not  a 
glyceride,  is  unsaponifiable.  Experiments  by  C.  Roth 
seem  to  show,  however,  that  this  view  is  erroneous. 

a.  Stretching  of  Yarn. — Those  yarns  which  are  hard 
twisted  require  this  preliminary  process  in  order  to  re- 
move their  curly  appearance  and  to  prevent  them  from 
shrinking  during  the  subsequent  scouring  operation.  For 
this  purpose  the  yarn-stretching  J;  machine  (Fig.  31) 
is  employed. 

It  consists  of  two  vertical  iron  screws  D,  connecting 
two  horizontal  bars,  a,  b,  one  above  the  other,  each  fitted 
with  a  series  of  metal  pegs  or  arms  c,  on  which  the  hanks 
are  suspended.  The  lower  bar  b  is  fixed,  while  the  upper 
one  A  is  capable  of  being  moved  up  or  down  by  turn- 
ing the  vertical  iron  screws,  and  fixed  at  any  point. 
After  filling  the  arms  c  with  yarn,  as  indicated  in  the 
figure,  the  bar  A  is  screwed  up  until  the  yarn  is  suitably 
stretched.  In  this  condition  the  whole  apparatus  is  im- 
mersed in  a  bath  of  boiling  water,  and  after  a  few 
minutes  removed.  Those  portions  of  the  hanks  immedi- 
ately in  contact  with  the  pegs  are  still  unaffected  and 
look  curly.  Hence  after  relaxing  the  tension  of  the 
hanks,  their  positions  on  the  pegs  are  changed,  they  are 
again  screwed  up,  and  the  immersion  in  boiling  water  is 
repeated.  When  taken  out  and  allowed  to  cool,  the  yarn 
is  taken  off  ready  for  scouring. 

b.  Scouring  Yarn. — Yarn  scouring  is  generally  done 
by  hand  in  an  ordinary  rectangular  wooden  tank,  the 
liquor  being  heated  by  means  of  a  perforated  copper 
steam-pipe.  The  hanks  are  suspended  on  smooth  wooden 
rods  placed  across  the  tank,  on  each  side  of  which  stands 
a  workman.  One  by  one  the  rods  full  of  yarn  are  taken 
up,  once  or  twice  swayed  to  and  fro,  and  then  each  hank 
is  carefully  lifted  up  and  turned,  so  that  the  exposed 
portion  resting  on  the  rod  may  become  immersed.  This  is 
frequently  facilitated  by  means  of  a  second  and  thinner 
rod,  which  is  inserted  in  the  loop  of  the  hanks,  im- 
mediately beneath  the  suspending  rod,  so  that  the  whole 
rod  full  of  hanks  may  be  turned  at  once,  and  without 


WOOL  SCOURING  AND  BLEACHING.  109 

scalding  the  hands.  The  whole  operation  is  systematic- 
ally repeated  during  15-20  minutes,  after  which  the  yarn 
is  transferred  to  a  second  tank  containing  cleaner  scour- 
ing liquid.    Here  the  process  of  turning  is  repeated,  after 


which  the  yarn  is  washed,  either  by  the  same  method  or 
by  placing  the  rods  full  of  hanks  on  a  pair  of  horizontal 
bars,  situated  beneath  a  perforated  wooden  tray,  on  which 
water  is  flowing;  the  yarn  thus  receives  an  efficient 
shower  bath. 


110 


TEXTILE  FABRICS. 


Scouring  partly  by  hand  and  partly  by  machine  is 
effected  by  the  apparatus  represented  in  Fig.  32.  The 


Fig-.  34. — Woollen  Cloth -scouring  Machine. 

yarn  is  suspended  on  reels  projecting  from  one  side  of 
the  scouring  box,  and  caused  by  steam-power  to  revolve 
in  the  scouring  solution  alternately  in  each  direction  for 


WOOL  SCOURING  AND  BLEACHING.  Ill 


a  short  time.  The  hanks  are  then  taken  off  the  reels, 
placed  on  a  moving  endless  band,  and  thus  led  through 
a  pair  of  squeezing  rollers,  to  be  washed  with  water  in 
a  similar  machine.  In  some  machines  the  reels  are 
omitted,  and  the  hanks  worked  in  the  liquid  by  hand. 

A  perfectly  continuous  method  of  scouring  by 
machinery  alone  is  that  in  which  the  loose  hanks  of  yarn 
are  placed  on  a  feeding  apron,  and  borne  along  between 
two  broad  endless  bands,  through  a  succession  of  scour- 
ing baths  fitted  with  a  series  of  squeezing  rollers. 


Fig.  35. — Section  of  Machine  shown  in  Fi«f.  34. 

Another  continuous  method  is  that  carried  out  by 
means  of  the  machine  represented  in  Fig.  33. 

The  hanks  are  linked  together  by  means  of  a  small 
knotted  and  twisted  loop  of  cord.  The  chain  of  yarn 
thus  formed  is  then  passed  continuously  through  a  series 
of  three  machines,  similar  to  the  one  represented,  c.  The 
squeezing  rollers,  A  and  b,  are  thickly  covered  with  some 
soft,  durable  material,  such  as  silk  noils. 

Cloth  Scouring. — Woollen  cloth  is  either  scoured  in 
the  "  rope  "  form  or  in  the  open  width,  the  latter  being 
the  preferable  mode,  since  the  operation  cannot  but  be 


112 


TEXTILE  FABRICS. 


thus  more  evenly  performed,  and  does  not  tend  to  produce 
creases  in  the  material. 

Figs.  34  and  35  represent  (in  perspective  and  in  sec- 
tion) the  common  rope-scouring  machine,  usually  termed 
a  "  dolly. ;;    It  consists  essentially  of  a  pair  of  heavy 


Fig-.  36. — Woollen  Cloth.  Open-width  Scouring  Machine. 

wooden  squeezing  rollers  (a  b),  placed  over  a  box  or 
trough  c,  containing  the  scouring  solution.  The  pieces 
are  stitched  end  to  end,  to  form  an  endless  band,  and  this 
is  made  to  pass  continuously  for  twenty  minutes  or  so 
between  the  rollers,  the  lower  one  of  which,  since  it  is 
partially   immersed,   carries  the   solution   to  the  cloth. 


WOOL  SCOURING  AND  BLEACHING.  113 


D  is  a  steam  pipe  for  heating  the  scouring  solution,  e 
an  empty  wooden  box,  F  and  G  are  guiding  rollers.  The 
operation  is  repeated  with  fresh  solution  in  another  simi- 
lar machine,  and  the  pieces  are  afterwards  washed  with 
clean  water. 

The  machine  employed  for  scouring  cloth  in  the  open 
width  is  shown  in  Fig.  36.  It  is  much  broader  than  the 
one  just  described,  in  order  to  suit  the  width  of  the 
cloth,  and  certain  straining  bars  f  are  required  for  the 
purpose  of  keeping  the  cloth  opened  out  and  free  from 
creases  previous  to  its  passage  between  the  squeezing 
rollers  a,  b,  which  are  preferably  of  iron,  in  order  to 
give  a  more  equal  pressure  across  the  whole  width  of  the 
cloth.  Immediately"  below  these  rollers  is  the  trough  0 
containing  the  scouring  solution.  The  perforated  water- 
pipe  H  is  used  when  the  pieces  are  washed  in  this  machine 
after  scouring. 

Scouring  Union  Material. — The  scouring  of  thin 
materials  with  cotton  warp  and  woollen  weft  presents 
certain  difficulties.  The  different  hydroscopic,  elastic, 
and  other  physical  properties  of  cotton  and  wool,  cause 
such  materials,  if  simply  scoured  in  the  ordinary  way, 
to  contract  or  shrink  irregularly  over  the  whole  surface 
of  the  fabric,  so  that  they  assume,  when  dried,  a  rough, 
shrivelled  appearance  which  renders  them  quite  unsale- 
able. Special  appliances  and  methods  are  in  consequence 
required.  The  scouring  of  thin  union  goods  comprises 
the  operations  of  Crabbing,  Steaming,  and  Scouring. 

(a)  Grabbing  or  Fixing. — The  object  of  this  and  the 
following  operation  is  to  prevent  the  material  from  ac- 
quiring the  "  cockled/7  "  curled,"  or  shrivelled  appear- 
ance above  alluded  to.  It  also  imparts  a  permanent  and 
indestructible  lustre  and  finish  of  a  peculiar  quality, 
which  is  not  removed  or  affected  by  any  subsequent  opera- 
tion. 

Fig.  37  shows  the  arrangement  of  a  treble  crabbing 
machine. 

The  cloth  a  wrapped  on  the  roller  or  beam  b  is  passed 
in  the  open  width,  and  in  a  state  of  tension,  below  the 
roller  D,  and  through  the  boiling  water  contained  in  the 
vessel  c,  then  immediately  between  the  pair  of  heavy 
iron  rollers  B  and  E,  under  great  pressure.    It  is  at  once 

H 


WOOL  SCOURING  AND  BLEACHING.  1U 


tightly  wrapped  or  beamed  on  the  lower  roller  b, 
while  still  revolving  in  the  hot  water.  The  process 
is  repeated  with  boiling  water  in  the  second  trough,  and 
again  with  cold  water  in  the  third  trough.  The  tension 
of  the  cloth  and  the  pressure  of  the  rollers  are  varied 
according  to  the  quality  of  the  goods,  and  the  particular 
feel,  lustre,  and  finish  ultimately  required.  With  goods 
that  must  have  subsequently  a  soft  feel  or  "  handle, " 
such  as  Cashmeres,  Coburgs,  etc.,  pressure  is  not  em- 
ployed, the  pieces  being  simply  beamed  tightly  on  the 
bottom  roller. 

(b)  Steaming. — The  pieces  are  unwrapped  from  the 
last  crabbing  roller  (that  is,  from  the  cold  water),  and 
tightly  wrapped  on  the  perforated  revolving  iron  cylin- 
der G.  Steam  is  admitted  through  the  axis  of  this 
cylinder  for  the  space  of  about  ten  minutes,  or  until  it 
passes  freely  through  the  cloth.  In  order  to  submit  every 
portion  of  the  piece  to  an  equal  action  of  the  steam,  the 
process  is  repeated  with  the  cloth  tightly  beamed  on  a 
second  and  similarly  perforated  roller  g',  so  that  those 
portions  of  the  cloth  which  were  on  the  outside  are  now 
in  the  interior.  These  perforated  steam-cylinders  are 
frequently  quite  separated  from  the  crabbing  machine, 
and  then  usually  rest  on  a  steam  nozzle  in  a  vertical  or 
horizontal  position. 

(c)  Scouring. — The  cloth,  being  now  "  set/'  as  it  is 
technically  termed,  is  scoured  for  half  an  hour  or  more, 
with  soap  solution  at  40°-50°  C.  in  the  "  Dolly  or 
"  open  width  "  machine,  above  described. 

The  sequence  of  operations  as  here  given,  although 
frequently  employed,  is  not  altogether  rational. 

The  best  results  are  obtained  by  crabbing  and  scour- 
ing simultaneously,  and  then  steaming.  To  accomplish 
this,  the  boiling  water  in  the  crabbing  troughs  is  merely 
replaced  by  a  solution  of  soap,  sodium  carbonate,  or  other 
scouring  agent.  It  is  found  that  to  steam  the  cloth  in 
its  oily  state  exercises  some  injurious  action,  and  renders 
it  liable  to  contract  dark  stains  during  mordanting, 
especially  if  stannous  mordants  are  employed.  It  is' 
possible  that  the  oil  is  more  or  less  decomposed,  and  a 
portion  becomes  fixed  on  the  fibre. 

Bleaching   Wool. — Wool  is  generally  bleached  either 


116 


TEXTILE  FABRICS. 


in  the  form  of  yarn  or  cloth,  but  only  when  it  is  intended 
to  remain  white,  or  if  it  has  to  be  dyed  in  very  light 
delicate  colours.  The  bleaching  agent  universally  adopted 
is  sulphur  dioxide.  According  to  the  state  in  which  it 
is  applied,  either  in  the  form  of  gas  or  dissolved  in 
water,  one  may  distinguish  between  "  gas  bleaching  77 
and  "  liquid  bleaching,77  and  of  these  the  former  is  more 
generally  employed.  In  recent  years  peroxide  of  hydro- 
gen has  come  to  the  front,  and  is  gradually  being  adopted 
for  this  purpose. 

Gas  Bleaching,  Stoving,  or  Sulphuring. — Yarn  is  first 


Fig.  38.— Sulphur  Stove  for  Woollen  Cloth  Bleaching-. 


scoured  and  well  washed,  then  suspended  on  poles  and 
placed  in  the  sulphur  stove — a  spacious  brick  chamber 
which  can  be  charged  with  sulphur  dioxide.  The  neces- 
sary amount  of  sulphur  (in  the  proportion  of  6-8  %  of 
the  wool  to  be  bleached)  is  placed  in  an  iron  pot  in  one 
corner  of  the  chamber,  and  ignited  by  inserting  a  hot 
iron ;  the  chamber  is  then  closed,  and  the  moist  yarn  is 
left  exposed  to  the  action  of  the  gas  for  6-8  hours,  or  even 
overnight.  Afterwards  the  chamber  is  thoroughly  ven- 
tilated; the  yarn  is  removed  and  well  washed  in  water. 
Heavy  woollen  cloth,  such  as  blanketing,   is  treated 


WOOL  SCOURING  AND  BLEACHING. 


117 


in  exactly  the  same  manner  as  yarn,  but  with  thin 
material— e.g.  merino,  etc. — the  operation  is  preferably 
made  continuous  by  adopting  the  arrangement  of  stove 
shown  in  Fig.  38.  It  is  provided  internally  with  a 
wooden  frame,  having  rollers  above  and  below.  The  roof 
should  be  lined  with  lead,  and  heated  with  steam  pipes, 
in  order  to  prevent  condensation.  The  stove  is  charged 
with  sulphur  dioxide  as  already  described,  or,  prefer- 
ably, the  sulphur  is  burnt  in  a  separate  furnace,  and  the 
gaseous  product  is  led  underneath  the  perforated  tile 
floor  of  the  stove.  The  cloth  is  introduced  through  a 
narrow  slit  in  the  wall ;  it  then  passes,  as  indicated, 
under  and  over  the  rollers,  and  passes  out  again  by  the 
same  opening.  The  number  of  times  the  cloth  is  passed 
through  the  stove  varies  according  to  the  appearance  of 
the  cloth. 

In  liquid  bleaching,  the  woollen  material  is  worked 
and  steeped  for  several  hours  either  in  a  solution  of  sul- 
phurous acid  or  in  a  solution  containing  sodium  bisul- 
phite (5-50  g.  per  litre),  to  which  an  equivalent  amount 
of  hydrochloric  acid  has  been  added ;  it  is  afterwards 
thoroughly  washed.  A  better  method,  however,  is  that  in 
which  the  wool  is  treated  with  sodium  bisulphite  and  by 
hydrochloric  acid  in  separate  baths,  whereby  the  sul- 
phurous acid  is  generated  within  the  fibre,  and,  being  in 
the  nascent  state,  acts  more  powerfully  upon  the  colour- 
ing matter  of  the  wool.  Goods  which  have  to  remain 
white  are  tinted  with  some  blue  or  bluish-violet  colour- 
ing matter  (such  as  ground  indigo,  indigo-extract  aniline 
blue,  etc.),  either  before  or  after  the  bleaching  operation, 
in  order  to  counteract  the  yellow  colour  of  the  wool  which 
is  so  apt  to  return.  The  principle  here  applied  is  that 
of  the  complementary  colours,  which,  when  mixed  in  due 
proportion,  produce  white  light.  Blue  is  complementary 
to  yellow. 

The  bleaching  action  of  sulphur  dioxide  is  most  prob- 
ably due  to  its  reducing  action  upon  the  natural  yellow 
colouring  matter  of  the  wool ;  another  explanation,  how- 
ever, is  that  it  combines  with  the  latter  to  form  a  colour- 
less compound.  Certain  it  is  that  the  effect  is  by  no 
means  permanent;  frequent  washing  of  bleached  wool  in 
alkaline   solutions   always  tends  to   restore   the  yellow 


118 


TEXTILE  FABRICS. 


appearance  of  the  fibre.  Either  oxidation  is  thus  induced, 
or  the  colourless  sulphite  is  decomposed,  and  the  original 
colouring  matter  is  precipitated  on  the  fibre. 

The  agent  par  excellence  for  liquid  bleaching  is  per- 
oxide of  hydrogen  (H202).  Even  yellow-coloured  wool  is 
bleached  by  it  to  a  white,  possesssing  a  brilliancy  and 
purity  unattainable  by  the  ordinary  methods.  The 
woollen  material  is  steeped  for  several  hours  in  a  dilute 
and  slightly  alkaline  solution  of  commercial  peroxide  of 
hydrogen  and  afterwards  well  washed,  first  with  water 
acidulated  with  sulphuric  acid,  and  afterwards  with 
water  only. 


119 


CHAPTER  IX. 

SCOURING    AND   BLEACHING  SILK. 

Object  of  Scouring  Silk. — The  object  of  scouring  silk 
is  to  remove  from  the  raw  fibre  a  greater  or  less  propor- 
tion of  the  silk-glue  which  envelops  it,  and  thus  to  render 
it  lustrous  and  soft,  and  better  fitted  for  the  operation 
of  dyeing.  According  to  the  amount  of  silk-glue  removed, 
the  product  of  the  scouring  operation  may  be  either 
boiled-off  silk,  souple  silk,  or  ecru,  for  each  of  which, 
indeed,  a  different  treatment  is  necessary. 

Boiled-off  Silk  is  the  name  given  to  silk  from  which 
practically  the  whole  of  the  silk-glue  has  been  removed. 
It  exhibits  most  fully  the  valued  properties  of  lustre, 
softness,  etc.  Two  operations  are  necessary  for  its  pro- 
duction, namely,  "  degumming  "  and  "  boiling-oftV' 

(a)  Degumming  (Fr.,  degommage). — The  object  of  this 
operation  is  to  soften  the  silk,  and  to  remove  the  great 
bulk  of  the  silk-glue  and  also  the  colouring  matter.  The 
hanks  of  raw  silk  are  suspended  on  smooth  wooden  rods, 
and  worked  by  hand  in  rectangular  copper  troughs,  in 
a  solution  of  30-35  %  soap,  heated  to  90°-95°  C.  When 
the  water  is  very  calcareous,  the  silk  is  first  rinsed  in 
a  weak,  tepid  solution  of  sodium  carbonate.  The  best 
plan  is  to  correct  the  water  previously.  Rinsing  in  dilute 
tepid  hydrochloric  acid  before  degumming  is  also  good, 
since  it  removes  calcareous  and  other  mineral  matters 
from  the  silk,  and  prevents  their  action  in  the  soap  bath. 
Weighted  ecru  silks  cause  great  inconvenience  in  the 
degumming  :  the  soap  bath  is  precipitated,  the  fibre  be- 
comes tarnished  and  sticky,  and  the  degumming  is  ren- 
dered difficult  and  incomplete. 

During  the  stripping  operation  the  silk  at  first  swells 
up  and  becomes  glutinous,  but,  after  a  short  time,  when 
the  silk-glue  dissolves  off,  it  becomes  fine  and  silky.  It 
is  best,  especially  when  the  silk  is  intended  for  whites 
gr  delicate  colours,  to  work  it  successively  in  two  or  three 


120 


TEXTILE  FABRICS. 


separate  baths,  for  about  20-25  minutes  in  each,  and  to 
pass  fresh  lots  of  silk  through  in  regular  order.  When 
the  first  bath  becomes  charged  with  silk-glue  it  is  re- 
newed, and  then  employed  as  the  last  bath.  Each  soap 
bath  should  be  utilised  to  the  fullest  extent  compatible 
with  excellence  of  result.  It  is  well  to  bear  in  mind  that 
too  prolonged  contact  with  boiling  soap  solution  is  not 
good,  since  a  little  of  the  colouring  matter  of  the  glue  is 
apt  to  be  attracted  by  the  fibre, '  and  the  silk  loses  sub- 
stance, strength,  and  purity  of  white.  The  waste  soapy 
and  glutinous  liquid  obtained  is  called  "  boiled-off  77 
liquor,  and  serves  as  a  useful  addition  to  the  dye-bath 
when  dyeing  with  the  coal-tar  colours. 

After  "  degumming,77  the  hanks  are  rinsed  in  wTater,  in 
which  a  small  quantity  of  soap  and  sodium  carbonate 
has  been  dissolved. 

(b)  Boiling-off  (Fr.,  la  cuite). — For  the  purpose  of 
removing  the  last  portions  of  silk-glue,  etc.,  and  to  give 
the  silk  its  full  measure  of  softness  and  lustre,  it  is  now 
placed  in  coarse  hempen  bags,  technically  called 
"  pockets,77  about  15  kg.  in  each,  and  boiled  from  half  an 
hour  to  three  hours  (according  to  the  quality  of  the 
silk)  in  large,  open  copper  vessels,  with  a  solution  of 
10-15  %  of  soap.  The  silk  is  then  rinsed  in  tepid  water, 
rendered  slightly  alkaline  by  the  addition  of  sodium  car- 
bonate in  order  to  prevent  the  precipitation  of  lime  soap 
on  the  silk.  It  is  finally  washed  well  in  cold  water. 
The  waste  soap  liquor  may  be  used  for  "  degumming.77 
For  some  articles,  the  silk  is  boiled  on  wooden  rods  and 
not  in  pockets. 

The  soap  employed,  both  for  "  degumming  77  and  for 
"  boiling-off,77  should  be  of  the  best  quality.  Other  things 
being  equal,  those  soaps  are  to  be  preferred  which  wash 
off  most  readily,  and  leave  an  agreeable  odour.  When, 
however,  the  silk  has  subsequently  to  undergo  a  num- 
ber of  soaping  and  other  operations — as  in  weighted 
blacks — the  odour  of  the  soap  used  in  boiling-off  is  of 
little  consequence.  Oleic  acid  soap  may  be  recommended 
in  such  a  case,  but  for  silk  destined  to  be  dyed  in  light 
colours  or  to  remain  white,  a  good  olive-oil  soap  is 
preferable. 

By  scouring  with  soap  in  the  above  manner,  Japanese 


SCOURING  AND  BLEACHING  SILK.  121 


and  Chinese  silks  lose  18-22  %  of  their  weight  and  Euro- 
pean silks  25-30  %. 

Stretching  (Fr.,  etirage). — When  the  silk  is  well  soft- 
ened during  the  stripping  process,  but  not  really  de- 
gummed,  it  may  be  conveniently  stretched  to  the  extent 
of  2-3  %  without  injury;  indeed,  it  acquires  increased 
lustre  by  stretching.  The  operation  may  be  performed 
either  by  the  lustring  or  the  stringing  machine. 

Stoving. — When  the  silk  is  intended  to  remain  white, 
or  is  to  be  dyed  pale  colours,  it  is  bleached  by  exposing 
it  in  a  moist  condition  to  the  action  of  sulphurous  acid 
in  closed  chambers.  The  operation,  which  lasts  about 
six  hours,  may  be  repeated  2-8  times,  according  to  the 
nature  of  the  silk.  Ten  kg.  of  silk  will  require  about 
\  kg.  of  sulphur.  After  stoving  the  silk  is  well  washed 
till  free  from  sulphurous  acid. 

Souple  silk  is  silk  which  has  been  submitted  to  certain 
operations,  to  render  it  suitable  for  dyeing,  etc.,  without 
causing  it  to  lose  more  than  4-8  %  of  its  weight.  The 
object  of  soupling  is,  indeed,  to  give  to  raw  silk,  if 
possible,  all  the  properties  of  boiled-off  silk,  with  the 
least  loss  of  weight ;  considerable  perfection  has  already 
been  attained  in  this  direction.  Souple  silk  is  not  so 
strong  as  boiled-off  silk,  and  is  used  for  only  tram. 

The  process  of  soupling  consists  essentially  of  two 
operations:  first,  the  softening;  and  second,  the  soupling 
proper.  With  yellow  silk,  and  whatever  is  intended  to  be 
dyed  light  colours,  the  operations  of  bleaching  and  stov- 
ing intervene. 

(a)  Softening. — The  raw  silk  is  worked  for  1-2  hours 
in  a  solution  of  10  %  soap,  heated  to  25°-35°  C.  The  ob- 
ject of  this  operation  is  to  soften  the  fibre,  and  remove 
the  small  quantity  of  fatty  matter  present,  so  as  to 
facilitate  the  operations  which  follow. 

(b)  Bleaching.— The  silk  is  worked  in  stone  troughs 
for  8-15  minutes  in  a  dilute  solution  of  aqua  regia  4°  Tw. 
(Sp.  Gr.  1-02),  heated  to  20°-35°  C.  It  is  afterwards 
washed  well  till  free  from  acid. 

The  aqua  regia  is  prepared  by  mixing  together  five 
parts  by  weight  of  hydrochloric  acid,  32°  Tw.  (Sp.  Gr. 
1*16),  with  one  part  of  nitric  acid,  62°  Tw.  (Sp.  Gr.  l'3l), 
and  allowing  the  mixture  to  stand  for  4-5  days  at  a 


122 


TEXTILE  FABRICS. 


temperature  of  about  25°-30°  C.  Before  use  it  is  diluted 
with  fifteen  volumes  of  water.  For  the  aqua  regia  may 
be  substituted  sulphuric  acid  saturated  with  nitrous 
fumes,  or  a  solution  of  the  so-called  "  chamber-crystals/' 
obtained  in  the  manufacture  of  sulphuric  acid. 

The  silk  must  not  be  worked  too  long  in  the  acid 
liquid,  otherwise  the  nitric  acid  causes  it  to  contract  a 
yellowish  tint  which  cannot  be  removed.  The  moment 
the  silk  has  acquired  a  greenish-grey  colour  it  should  be 
withdrawn  from  the  bath,  and  well  washed  with  cold 
water. 

(c)  Stoving. — This  operation  is  similar  to  that  already 
described.  It  renders  the  silk  hard  and  brittle.  Without 
removing  the  sulphurous  acid,  however,  it  is  at  once 
submitted  to  the  following  operation  : — 

(d)  Soupling  (Fr.,  assouplissage). — The  silk  is  worked 
for  about  an  hour  and  a  half,  at  90°-100°  C,  in  water, 
containing  in  solution  3-4  g.  cream  of  tartar  per  litre. 
The  silk  becomes  softer  and  swells  up,  and  being  thus 
rendered  more  absorbent,  it  is  better  adapted  for  dyeing. 
The  operation  of  soupling  is  a  somewhat  delicate  one, 
and  needs  considerable  judgment  and  practice.  The  solu- 
tion must  not  be  too  hot,  nor  must  the  immersion  of  the 
silk  be  too  prolonged,  otherwise  the  loss  in  weight  is 
excessive,  and  the  result  is  unsatisfactory.  After  soup- 
ling the  silk  is  finally  worked  in  a  bath  of  tepid  water. 
Souple  silk  will  bear  warm  acid  baths  subsequently,  but 
not  alkaline  or  soap  baths  beyond  a  temperature  of 
50°-60°  C,  otherwise  it  loses  silk-glue,  and  is  more  or 
less  spoiled.  The  operation  of  soupling  is  sometimes  per- 
formed on  raw  silk  which  has  been  previously  submitted 
to  other  operations,  as,  for  example,  in  the  dyeing  of 
so-called  black  souples. 

A  satisfactory  explanation  of  the  theory  of  soupling 
has  not  yet  been  given.  The  cream  of  tartar  probably 
acts  as  an  acid  salt  merely,  and  although  it  gives  the  best 
results,  it  can  be  replaced  by  a  solution  of  sodium  or 
magnesium  sulphate  acidified  with  sulphuric  acid,  or 
even  by  very  dilute  hydrochloric  acid.  It  is  curious  that 
silk  is  rendered  less  tenacious  by  soupling  than  by 
boiling-off. 

Ecru  Silk  is  raw  silk  which  at  most  is  submitted  to 


SCOURING  AND  BLEACHING  SILK.  123 


washing,  with  or  without  soap,  and  bleaching.  The  loss 
of  weight  varies  from  1-6  %.  Unbleached  ecru  silk  is 
only  dyed  in  one  or  two  different  shades  of  black. 

Bleaching  Tussur  Silk. — This  may  be  accomplished 
according  to  the  method  proposed  by  M.  Tessie  du  Motay, 
in  which  barium  binoxide  is  the  agent  employed.  Free 
baryta  hydrate  is  first  removed  from  the  binoxide  by 
washing  the  latter  with  cold  water,  and  a  bath  is  then 
prepared,  containing  binoxide  in  the  proportion  of  50- 
100  %  of  the  weight  of  silk  to  be  bleached. 

The  silk  is  washed  for  about  an  hour  in  the  bath 
heated  to  80°  C,  then  washed  and  passed  into  dilute 
hydrochloric  acid,  and  washed  again.  If  the  white  is 
not  good,  the  operations  are  repeated,  or  one  may  also 
complete  the  bleaching  by  washing  the  silk  in  a  solution 
of  potassium  permanganate  and  magnesium  sulphate,  and 
afterwards  in  a  solution  of  sodium  bisulphite,  to  which 
hydrochloric  acid  has  been  added. 

Although  barium  binoxide  is  little  soluble  in  water, 
at  the  temperature  of  the  bleaching  bath  it  gives  up 
oxygen  to  the  fibre  by  degrees,  even  without  the  addition 
of  any  acid,  so  that  the  bleaching  takes  place  gradually. 
During  the  immersion  the  silk  also  absorbs  a  certain 
amount  of  the  binoxide,  probably  as  hydrate,  so  that  on 
the  subsequent  passage  into  acid  there  is  liberated  within 
the  fibre  hydrogen  dioxide,  which,  being  in  the  nascent 
state,  bleaches  to  the  best  effect. 

The  chief  difficulty  of  the  process  consists  in  the  fact 
that,  by  long  contact  with  the  barium  binoxide,  the  silk 
becomes  dull,  harsh,  and  tender,  but  with  care  the  process 
can  be  made  to  yield  excellent  results  and  it  is,  indeed, 
already  adopted  in  practice.  Hypochlorite  of  ammonia 
has  been  employed,  but  with  less  success.  The  best  bleach- 
ing agents  for  Tussur  and  also  Mulberry  silk  are  per- 
oxide of  hydrogen  and  peroxide  of  sodium,  especially  the 
former. 

Tussur  silk  is  bleached  for  the  purpose  of  dyeing  it  in 
light  colours,  and  a  good  bath  is  made  up  of  a  mixture  of 
caustic  soda,  white  curd  soap,  peroxide  of  hydrogen,  and 
a  little  ammonia, 


124 


CHAPTER  X. 

WATER. 

Soft  and  Hard  Water. — Natural  water  occurs  in  the  form 
of  invisible  vapour  permeating  the  air.  When  the  tem- 
perature becomes  sufficiently  low,  the  vapour  condenses 
and  becomes  visible  as  dew,  fog,  or  cloud,  or  is  precipi- 
tated in  the  form  of  rain.  The  original  source  of  natural 
water  is  the  ocean.  This  is  in  a  state  of  constant  evapora- 
tion, and  the  vapour  produced  just  as  constantly  under- 
goes the  condensation  alluded  to.  Indeed,  a  gigantic 
process  of  natural  distillation  is  here  presented,  and,  as 
one  would  anticipate,  rain-water  is  the  purest  form  of 
natural  water. 

A  portion  of  the  rain-water  sinks  into  the  earth  until 
it  reaches  some  impervious  layer,  from  which  it  may  be 
pumped  up  as  well-water,  or  it  flows  underground,  and 
eventually  reappears  on  the  surface  as  a  spring,  which 
frequently  forms  the  source  of  a  brook  or  river. 

Another  portion  of  the  rain-water  never  penetrates 
the  soil,  but  simply  drains  off  the  land,  and  forms  the  so- 
called  surface-water,  which  also  goes  to  form  rivers. 

The  solvent  power  of  water  is  so  considerable  that 
both  spring  and  river  water  always  contain  certain 
mineral  and  vegetable  matters,  the  nature  of  which  varies 
according  to  the  character  of  the  rock  or  soil  through 
or  over  which  it  has  passed. 

If  the  geological  strata  are  composed  of  such  hard 
insoluble  rocks  as  granite  and  gneiss,  the  water  remains 
comparatively  free  from  impurities,  and  whether  it  flow 
as  a  river  or  rise  as  a  spring,  it  will  be  what  is  termed 
a  "  soft  "  water. 

If,  on  the  contrary,  the  water  during  its  subterranean 
course  meets  with  rocks  containing  such  a  soluble  con- 
stituent as  rock-salt,  it  becomes  brine ;  if  it  encounters  a 
stratum  of  limestone,  oolite,  chalk,  new  red  sandstone, 
etc.,   it  dissolves  a  certain  portion  of  it,  and  becomes 


WATER. 


125 


magnesian  or  calcareous,  and  constitutes  on  its  reappear- 
ance what  is  called  a  "  hard  ;;  water.  Common  lime- 
stone being  generally  of  a  less  permeable  nature  than 
magnesian  limestone,  does  not  yield  such  hard  water  as 
the  latter.  Again,  if  the  water  passes  through  or  over 
rocks  containing  iron  in  some  form  or  other,  it  takes  up 
some  of  the  iron  and  becomes  a  so-called  "  chalybeate  " 
water.  When  the  rain-water  drains  from  boggy  moor- 
land, a  certain  portion  of  the  more  or  less  decomposing 
vegetable  matter  dissolves,  and  the  water  is  usually 
brown-coloured. 

The  natural  impurities  of  water  which  concern  the 
dyer  must  be  either  suspended  or  dissolved,  and  of  these 
the  latter  are  the  most  important.  A  constant  supply  of 
clear  water  is  certainly  an  indispensable  requisite,  but 
the  means  of  purifying  muddy  water  are  comparatively 
simple,  and  the  chemical  nature  of  the  suspended  matter 
generally  possesses  little  or  no  interest.  The  dissolved 
constituents  of  water,  however,  are  equally,  or  even  more, 
injurious,  and  to  effect  their  removal  is  much  more  diffi- 
cult, involving  as  it  does  the  employment  of  chemical 
means  of  purification.  As  a  general  rule,  river  water 
contains  the  largest  amount  of  suspended  and  vegetable 
matter,  and  the  least  amount  of  dissolved  constituents, 
whereas  spring  and  well  water  bear  the  opposite 
character. 

Calcareous  and  Magnesian  Impurities  in  Water. — 
These  are  at  once  the  most  frequently  occurring,  and  the 
most  injurious  of  all  impurities.  They  are  usually  pre- 
sent as  bicarbonates,  less  commonly  as  chlorides  and  sul- 
phates. The  latter  are  generally  less  injurious  than  the 
former. 

The  presence  of  lime  is  shown  if  the  addition  of  a 
solution  of  ammonium  oxalate  to  the  water  in  question 
gives  a  white  precipitate  of  calcium  oxalate.  On  evapo- 
rating such  a  water  to  a  small  bulk  it  becomes  turbid. 
If,  then,  the  addition  of  hydrochloric  acid  produces 
effervescence,  and  renders  the  solution  again  perfectly 
clear,  it  is  an  indication  that  all  the  lime  is  present  as 
bicarbonate.  If  there  is  no  effervescence  and  no  clearing, 
it  is  probably  all  present  as  sulphate.  Effervescence  and 
partial  clearing  denote  the  presence  of  both  sulphate  and 


126 


TEXTILE  FABRICS. 


carbonate.  Should  there  be  no  turbidity  on  evaporation, 
lime  is  either  absent  altogether,  or  it  is  probably  present 
as  chloride  or  nitrate. 

The  presence  of  magnesia  is  detected,  after  lime  and 
alumina  have  been  removed  by  means  of  ammonia  and 
ammonium  oxalate.  The  filtered  liquid  is  concentrated 
by  evaporation  and  mixed  with  a  solution  of  phosphate 
of  soda  and  ammonia;  magnesia  is  present  if  a  white 
crystalline  precipitate  is  thereby  produced.  The  separa- 
tion, however,  of  lime  and  magnesia  has  little  or  no 
importance  for  the  dyer. 

The  presence  of  bicarbonates  is  further  detected  by 
the  addition  of  a  clear  solution  of  lime-water  producing 
a  white  precipitate. 

Sulphates  are  present  if  an  addition  of  hydrochloric 
acid  and  barium  chloride  gives  a  white  precipitate. 

A  white  curdy  precipitate,  which  is  produced  on  add- 
ing nitric  acid  and  silver  nitrate,  denotes  the  presence 
of  chlorides. 

The  injurious  influence  of  magnesian  and  calcareous 
water  cannot  be  overrated,  and  very  specially  because  of 
its  property  of  precipitating  soap  solutions.  Hard  water 
only  produces  a  froth  or  lather  with  soap  after  the  whole 
of  the  calcium  and  magnesium  compounds  present  have 
been  precipitated  as  in  soluble  lime  and  magnesia  soaps, 
the  latter  of  which  may  be  distinguished  from  the  former 
by  their  more  objectionable  curdy  character. 

By  employing  a  soap  solution  of  a  standard  strength, 
it  is  possible  to  calculate  aproximately  the  amount  of 
calcium  and  magnesium  compounds  present.  Details  of 
this  method  of  determining  the  hardness  of  water 
(Clark's)  are  given  in  most  text-books  of  chemical 
analysis. 

It  is  well  to  note  that,  according  to  Clark's  scale,  a 
water  with  one  degree  of  hardness  contains  1  g.  calcium 
carbonate  per  gal.,  but  after  the  newer  scale  of  Frank- 
land,  one  degree  of  hardness  signifies  that  the  water  con- 
tains 1  g.  of  CaC03  in  100,000  g.  water.  To  reduce  the 
degrees  of  the  latter  to  those  of  Clark's  scale  it  is  simply 
necessary  to  multiply  by  seven-tenths. 

In  all  those  operations  where  large  quantities  of  soap 
are  employed,  it  is  evident  that  the  use  of  a  hard  water 


WATER. 


127 


entails  a  considerable  loss  of  soap.  One  part  (by  weight) 
of  CaO  is  found  to  decompose  about  15*5  parts  of  ordinary 
soap  containing  30  %  of  moisture.  After  making  a  soap- 
analysis  of  the  water,  and  knowing  the  quantity  of  the 
water  employed,  it  is  easy  to  calculate  the  annual  loss  of 
soap  (about  one-sixth)  occasioned  by  the  hardness  of  the 
water.  Taking  the  monthly  consumption  of  soap  in  Lon- 
don as  1,000,000  kg.  =  9482  tons,  it  is  estimated  that 
the  hardness  of  the  water  used  causes  an  expenditure  of 
230,000  kg.  =  226*36  tons  more  soap  per  month  than  would 
be  required  if  soft  water  were  used. 

This  is,  however,  by  no  means  the  only  disadvantage. 
The  precipitated  earthy  soaps  are  more  or  less  of  a  sticky 
nature,  and  adhere  so  tenaciously  to  the  fibre  that  they 
cannot  be  removed  by  ordinary  technical  processes.  In 
the  scouring  of  wool  or  of  silk  they  render  the  fibre  more 
or  less  impermeable,  so  that  neither  mordant  nor  colour- 
ing matter  can  be  afterwards  properly  fixed  thereupon, 
and  irregular  development  of  colour  results. 

When  the  soap  solutions  are  applied  after  dyeing — as  in 
the  clearing  of  Turkey-red,  milling  of  woollen  fabrics, 
etc. — the  precipitated  earthy  soaps  may  impart  to  the 
finished  fabric  a  pale  greyish  "  bloom, ;;  or  an  unnatural 
lustre,  and  altogether  ruin  both  the  brilliancy  of  the 
colour  and  the  value  of  the  fabric. 

In  some  cases  earthy  soaps  may  act  injuriously  by 
playing  the  role  of  mordants.  It  would  be  dangerous, 
for  example,  to  employ  soap  in  the  bleaching  of  calico 
for  printing  purposes,  or  to  re-dye  printed  calicoes  after 
soaping,  since  any  lime-soap  precipitated  on  the  fabric 
would  attract  colouring  matter,  and  cause  the  white 
ground  to  be  stained. 

Hard  water  is  also  injurious  in  the  dye-bath,  because 
it  only  imperfectly  extracts  the  colouring  matter  from  the 
dye  woods  employed.  Some  colouring  matters — Alizarin 
Blue,  Ccerule'in,  etc.,  also  Catechu  and  Tannin  matters — 
produce  insoluble  compounds  with  the  alkaline  earths, 
and  may  thus  be  precipitated  and  rendered  inactive. 

It  must  not  be  forgotten,  however,  that  the  presence 
of  a  certain  limited  amount  of  lime  is  beneficial,  and, 
even  necessary,  in  dyeing  with  some  colouring  matters — 
as  Alizarin,  Logwood,  Weld,  etc. — but  in  such  cases  even, 


128 


TEXTILE  FABEIG8. 


it  is  always  preferable  to  have  a  pure  water,  so  that  one 
may  add  the  most  suitable  form  and  amount  of  lime  salt. 

Hard  water  has  generally  the  effect  of  dulling  the 
colours  obtained  from  many  colouring  matters,  both  dur- 
ing the  dyeing  and  the  subsequent  washing  processes. 
When  the  hardness  is  due  to  the  presence  of  earthy 
bicarbonates,  it  retards  or  even  prevents  the  dyeing 
of  such  colours  as  are  produced  only  in  an  acid  bath,  as 
cochineal  scarlet. 

Such  water  acts  injuriously  also  on  solutions  of  cer- 
tain mordants — like  those  of  aluminium,  iron,  etc. — by 
neutralising  a  portion  of  their  acid  and  precipitating 
basic  salts,  the  mordanting  bath  being  then  less  effective. 

In  some  cases  of  mordanting,  however,  water  contain- 
ing earthy  bicarbonates  is  to  be  preferred  to  pure  water, 
since  it  fixes  a  much  larger  quantity  of  insoluble  basic 
salt  on  the  fibre,  as,  for  example,  in  the  washing  of  silk 
after  mordanting  with  basic  ferric  sulphate,  and  with 
aluminium  or  tin  mordants. 

Water  rich  in  earthy  bicarbonates  is  not  suitable  for 
the  solution  of  many  of  the  coal-tar  colours,  such  as 
Methyl  Violet,  etc.  A  portion  of  the  colour-base  is  pre- 
cipitated as  a  tarry  mass,  and  not  only  is  colouring 
matter  wasted,  but  goods  dyed  in  such  solutions  are  apt 
to  be  spotted. 

Ferruginous  Impurities  in  Water. — These  are  to  be 
looked  for  in  water  which  is  derived  from  disused  coal- 
pits, iron-mines,  iron  and  aluminous  shales,  etc.,  and 
are  also  very  objectionable  in  dyeing  operations.  Surface 
water  draining  off  moorland  districts  and  passing  over 
ochre-beds  also  contains  iron,  evidence  of  which  is  see?i 
in  the  brown  ferric  oxide  deposited  on  the  stones  in  the 
stream.    All  such  water  should  be  rigorously  avoided. 

To  test  for  the  presence  of  iron,  evaporate  some  of 
the  water  in  a  clean  porcelain  basin.  If  a  reddish-brown 
deposit  is  thereby  produced,  this  must  be  collected,  dis- 
solved in  a  little  hydrochloric  acid,  and  thoroughly 
oxidised  by  heating,  with  the  addition  of  a  little  potas- 
sium chlorate.  The  solution  is  diluted  and  cooled,  and 
a  solution  of  potassium  ferrocyanide,  or  thiocyanate,  is 
added.  If  iron  is  present,  a  blue  precipitate  or  red 
coloration,  respectively,  is  thereby  produced. 


WATER. 


129 


The  iron  being  usually  present  as  bicarbonate,  acts 
upon  soap  solutions  after  the  manner  of  the  analogous 
calcium  and  magnesium  compounds,  and  similar  or  even 
worse  results  ensue. 

In  wool-scouring,  cotton-bleaching,  and  other  opera- 
tions where  alkaline  carbonates  are  used,  ferric  oxide  is 
precipitated  upon  the  fibre.  With  such  goods  it  would 
be  quite  impossible  to  dye  bright  colours  subsequently — 
e.g.  alizarin  reds,  etc. — and  all  colours,  indeed,  suffer 
more  or  less.  Bleached  fabrics  acquire  an  unpleasant 
yellowish  tinge,  which  will  neither  rinse  nor  scour  out,  and 
which  renders  the  goods  quite  unsaleable. 

Alkaline  Carbonates  as  Imparities  in  Water. — Water 
containing  sodium  carbonate  is  frequently  met  with  in 
districts  where  the  supply  is  derived  from  wells  which 
penetrate  the  lower  beds  of  the  Coal  Measures.  This 
alkaline  condition  is  detected  by  means  of  red  litmus- 
paper. 

Such  water  is  by  no  means  detrimental  in  wool  scour- 
ing, or  in  operations  where  alkaline  carbonates  are 
nominal  constituents  of  the  bath,  if  other  injurious  con- 
stituents are  absent;  but  for  purposes  of  mordanting, 
dyeing,  and  washing  of  dyed  goods,  it  is,  if  possible,  more 
injurious  than  the  water  containing  earthy  carbonates. 
When  no  other  water  is  to  be  had,  it  must  for  such 
operations  be  carefully  neutralised  with  sulphuric  or 
acetic  acid. 

Acid  Salts  and  Free  Acids  as  Impurities  in  Water. — 
Water  draining  from  moorland  districts  contains  what 
are  usually  termed  peaty  acids,  and  since  these  attack 
iron  very  readily,  they  may  indirectly  cause  serious 
injury. 

Water  derived  from  shale  beds  containing  pyrites  and 
situated  near  the  surface,  becomes  contaminated  with  fer- 
rous sulphate.  On  exposure  to  air  this  salt  oxidises,  ferric 
oxide  is  deposited,  and  the  water  contains  free  sulphuric 
acid.  Blue  litmus-paper  serves  to  detect  the  presence 
of  this  impurity. 

Such  water  is  unsuitable  for  scouring  operations,  since 
it  decomposes  and  wastes  the  detergents  used.  If  soap  is 
employed,  fatty  acid  is  liberated  and  liable  to  be  fixed 
upon  the  fibre.  In  dyeing  operations  acid  water  is  equally 
I 


130 


TEXTILE  FABRICS. 


injurious.  If  such  water  cannot  be  avoided,  it  must  be 
carefully  neutralised  with  carbonate  of  soda. 

Organic  Impurities  in  Water. — These  as  they  exist  in 
moorland  streams  have  not  been  found  in  practice  to  be 
injurious,  unless  the  water  is  thereby  so  deeply  coloured 
as  to  stain  the  woollen  or  other  fibre,  which  is  to  be  dyed 
light  shades  only,  or  is  intended  to  remain  in  the  bleached 
condition.  In  the  absence  of  inorganic  reducing  bodies 
the  presence  of  organic  matter  is  determined  by  adding 
a  solution  of  permanganate  of  potash  sufficient  to  impart 
a  pink  colour,  acidifying  with  sulphuric  acid,  and  then 
boiling.  If  organic  matter  is  present  the  solution  is 
decolorised. 

Sulphuretted  Hydrogen  as  an  Impurity  in  Water. — 
This  is  only  occasionally  met  with,  and  arises  through  the 
decomposition  of  gypsum  by  organic  matter.  Such  water 
is  to  be  rejected,  since,  when  iron,  tin,  copper,  and  lead 
mordants  are  used,  sulphides  of  these  metals  are  formed, 
and  cause  black  or  brown  stains. 

This  impurity  is  detected  by  slightly  acidifying  the 
water  with  acetic  acid  and  placing  it  in  closed  flasks  in  a 
warm  place  for  some  time.  A  strip  of  filter  paper  mois- 
tened with  lead  acetate  is  fixed  above  the  surface  of  the 
liquid.  The  formation  of  brown  lead  sulphide  on  the 
filter  paper  denotes  the  presence  of  sulphuretted  hydrogen. 

Specially  injurious  are  the  impurities  which  may  come 
from  establishments  situated  higher  up  the  stream — e.fj. 
paper-works,  chemical-works,  bleach-works,  etc.  Hence 
the  dyer,  whose  only  source  of  supply  is  a  river  running 
through  a  manufacturing  district  must  be  specially  vigi- 
lant, for  although  the  pollution  of  rivers  by  waste  pro- 
ducts, etc.,  from  various  manufactories  may  be  forbidden, 
the  compliance  with  this  restriction  is  beset  in  many  in- 
stances with  enormous  difficulties  which,  indeed,  can  only 
be  partially  overcome. 

Correction  and,  Purification  of  Water. — Pure  water  is 
certainly  one  of  the  first  requisites  for  all  operations  of 
bleaching  and  dyeing.  Unfortunately  it  is  at  the  dis- 
posal of  few  manufacturers,  and  the  increasing  injury 
thus  caused  has  not  always  met  with  the  attention  it 
deserves.  Directors  of  bleach  and  dye  works  will  find  this 
subject  as  difficult  as  it  is  interesting  and  important. 


WATER: 


131 


Although  it  is  comparatively  easy  to  purify,  or  at  least 
to  correct,  small  quantities  of  water,  the  technical  problem 
of  readily  purifying  such  large  supplies  of  water  as  are 
necessary  for  dyeing,  etc.,  is  surrounded  with  difficulties. 
The  purification  of  water  usually  comprises  both  a 
mechanical  and  a  chemical  treatment. 

Mechanical  Purification  of  Water. — Whenever  the  land 
is  suitable,  the  water  is  collected  and  allowed  to  settle  in 
large  reservoirs,  even  if  only  for  the  purpose  of  storage. 
When  possible,  several  reservoirs  are  maintained,  and  it 
is  well  to  pass  the  water  from  one  to  the  other  in  such  a 
manner  as  to  expose  it  as  much  as  possible  to  the  air — 
for  instance,  by  a  staircase  cascade.  Finally,  the  water 
should  be  passed  through  filter-beds  of  sand.  During 
the  exposure  to  air  in  this  manner  a  partial  chemical 
purification  will  take  place  in  water  containing  calcium, 
magnesium,  or  iron  bicarbonates ;  a  portion  of  the  solvent 
carbonic  acid  is  lost  and  the  carbonates  are  precipitated. 

The  most  favourable  circumstance  is  that  in  which  the 
works  are  placed  upon  the  bank  of  a  river  flowing  from 
a  lake  situated  immediately  above,  so  that  neither  heavy 
rains  nor  melting  snow  will  render  the  water  turbid. 

Purification  of  Water  by  Boiling. — Reference  has  al- 
ready been  made  to  the  convenient  classification  of  "  soft  " 
and  "  hard  waters.  The  latter  may  be  sub-divided  into 
those  which  are  temporarily  hard,  and  those  which  are 
permanently  hard,  although  most  waters  combine  both 
properties. 

A  water  possessing  temporary  hardness  becomes  soft  by 
mere  boiling,  if  this  is  sufficiently  prolonged,  since  such 
hardness  is  due  to  magnesium,  calcium,  or  iron  bicar- 
bonates. The  effect  of  boiling  is  to  expel  one-half  of  the 
carbonic  acid,  and  thus  to  precipitate  the  insoluble  mono- 
carbonates  produced.  Since  the  softening  effect  takes 
place  only  gradually,  the  boiling  should  be  continued 
for  20-30  minutes  at  least.  It  is  scarcely  necessary  to  add 
that  this  method  of  purification  is  far  too  costly  to  serve 
for  large  quantities  of  water. 

A  water  which  is  permanently  hard  derives  this  pro- 
perty from  the  presence  of  sulphates  of  the  above- 
mentioned  metals ;  hence,  in  this  case,  boiling  has  no 
softening   influence;   on   the   contrary,    the   hardness  is 


132 


TEXTILE  FABRICS. 


increased  through  the  concentration  of  the  water,  and  other 
modes  of  purification  must  be  adopted. 

Chemical  Purification  of  Water. — As  to  the  purification 
or  correction  of  water  by  chemical  means,  one  element  of 
difficulty  is  the  inconstancy  of  the  composition  of  the 
water.  Heavy  rain  and  melting  snow  dilute  it,  while  hot 
summer  weather  concentrates  it,  especially  in  small  rivers. 
Whenever  it  is  impossible  to  keep  pace  with  varying  con- 
ditions of  this  kind  by  making  frequent  analyses  of  the 
water,  it  is  advisable,  in  the  absence  of  purification  or 
correction  on  a  large  scale,  to  add  to  the  water  such  agents 
as  are  not  specially  injurious,  even  if  added  in  slight 
excess.  In  many  cases  it  suffices  to  neutralise  as  care- 
fully as  possible  the  alkalinity  of  a  water  arising  from  the 
presence  of  earthy  bicarbonates  by  the  addition  of  acetic 
acid — e.g.  in  most  cases  of  dyeing,  or  for  the  purpose 
of  dissolving  coal-tar  colours.  An  old  method  of  purify- 
ing small  quantities  of  water  which  is  still  often  used  by 
silk  and  woollen  scourers,  etc.,  is  to  boil  the  water  with 
the  addition  of  a  little  soap,  with  or  without  the  addition 
of  sodium  carbonate,  and  to  skim  off  the  earthy  soaps 
thrown  to  the  surface.  Apart  from  its  expense,  this 
method  is  unsatisfactory,  since  the  major  portion  of  the 
earthy  soaps,  etc.,  remain  disseminated  in  the  water  in 
a  finely-divided  state.  Water  corrected  in  this  manner  is 
necessarily  left  in  an  alkaline  condition  from  the  alkali 
of  the  soap  remaining  behind,  and  of  course  the  amount 
of  alkaline  carbonate  left  is  equivalent  to  that  of  the 
earthy  salts  removed,  thus  : — 

CaH2(COs)2  +  2C18H3302Na  =  Ca(C18H3302)2  + 

Calcium  bicarbonate.  Scnp.  Lime-soap. 

Na2C03  +  C02  +  H20. 

Sodium  carbonate.  Water. 

The  dyer's  method  of  adding  alum  to  the  water  of  the 
mordanting  or  dye-bath,  and  then  boiling  and  skimming 
off  impurities  which  rise  to  the  surface,  is  even  more 
uncertain,  and  is  strongly  to  be  deprecated. 

Purification  of  Water  with  Lime.  Clark's  Process. — 
Since  calcium  and  magnesium  carbonates  are  soluble  in 
water  only  by  the  presence  of  carbonic  acid,  the  natural 
remedy  is  to  employ  some  means  which  will  rapidly  and 


WATER, 


133 


effectively  remove  or  absorb  the  latter.  In  1841  Dr.  Clark 
proposed  calcium  hydrate  or  slaked  lime  as  the  cheapest 
and  most  suitable  agent  for  this  purpose,  and  his  method, 
or  some  modification  of  it,  is  still  generally  adopted.  The 
following  equation  explains  the  theory  of  the  process  :  — 

CaH2(C03)2  +  Ca(OH)2  =  2CaC03  +  2H20. 

Calcium  Calcium  Calcium 

bicarbonate.  hydrate.  carbonate. 

In  carrying  out  the  method  here  expressed,  many 
practical  difficulties  are  met  with,  and  constant  skilled 
oversight  is  necessary  to  insure  success. 

Only  the  temporary  hardness  is  removed,  and  not  even 
this  completely.  A  small  residuum  of  chalk  always  re- 
mains in  solution.  It  is  quite  possible,  however,  to  remove 
10-llths  of  the  whole  temporary  hardness,  as  well  as 
iron  salts  and  much  organic  matter.  Experiments  on 
a  large  scale  have  proved  that,  by  the  lime  process,  water 
of  23°  hardness  can  be  reduced  to  7°,  of  15°  to  3°  or  4°, 
and  so  on. 

It  is  best  to  employ  clear  lime-water  for  correction, 
since  this  possesses  a  known  constant  composition.  The 
amount  of  such  lime-water  which  it  is  necessary  to  em- 
ploy may  be  calculated  after  making  an  analysis  of  the 
water,  or  may  be  determined  by  actual  experiment.  If 
the  number  of  degrees  hardness  (Clark's  scale)  is  divided 
into  130  or  150,  the  number  obtained  will  approximately 
represent,  as  a  rule,  the  number  of  litres  of  water  which 
can  be  softened  by  the  addition  of  one  litre  of  lime-water. 

Clear  lime-water  may  be  replaced  by  milk-of-lime,  if 
the  latter  is  carefully  applied.  Excess  of  lime  in  the  cor- 
rected water  is  readily  detected  by  adding  a  little  of  it  to 
a  filtered  decoction  of  cochineal.  Such  excess  changes  the 
yellowish-red  colour  of  the  solution  to  a  violet.  Other 
delicate  alkali-indicators  may  also  be  adopted. 

In  working  Clark's  process  as  originally  devised,  large 
tanks  or  reservoirs  are  requisite.  It  is  best  to  have  at 
least  three — one  into  which  to  run  the  water  and  lime 
and  to  allow  the  precipitated  chalk  to  settle  for  about  16 
hours;  another  from  which  clear  and  previously  cor- 
rected water  can  be  drawn ;  and  a  third  as  a  reserve 


134 


TEXTILE  FABRICS. 


during  cleansing  operations.  Each  reservoir  should  hold 
at  least  a  day's  supply. 

Purification  of  Water  with  Caustic  Soda.—  For  pur- 
poses of  scouring,  or  where  a  slightly  alkaline  water  is  not 
prejudicial,  caustic  soda  may  be  conveniently  substituted 
for  quicklime,  since  its  solution  can  so  readily  be  made 
of  a  standard  strength  and  added  in  the  requisite  amount 
to  the  water  to  be  corrected  : — 

CaH2(C03)2  +  2NaHO  =  CaC03  +  Na2C03  +  2H20. 

In  this  case,  of  course,  exactly  the  same  amount  of 


sodium  carbonate  remains  in  the  corrected  water  as  if 
the  purifying  agent  used  had  been  soap.  It  is  well  to 
heat  the  mixture  to  50°  C.  in  order  to  cause  more  rapid 
settling  of  the  precipitate.  Mechanical  impurities,  also 
iron,  aluminum,  and  earthy  phosphates  are  completely 
thrown  down. 

Permanent  as  well  as  temporary  hardness  is  removed 
by  the  use  of  caustic  soda,  since  the  calcium  and  mag- 
nesium sulphates  present  are  decomposed  by  the  sodium 
carbonate  produced  in  the  above  reaction. 

Should  the  water  corrected  in  this  manner  be  required 


WATER. 


135 


for  purposes  where  alkalinity  is  to  be  avoided,  it  can  be 
readily  neutralised  before  use. 

Porter-Clark  Process  of  Softening  Water. — The  essen- 
tial improvement  effected  by  this  process  is  a  saving  of 
space,  time,  and  labour,  through  the  application  of 
machinery  -to  the  ordinary  Clark's  process. 

Figs.  39  and  40  give  plan  and  elevation  of  an  arrange- 
ment for  supplying  over  6,000  litres  —  1,320*58  gals,  of 


Fig.  40.— Porter-Clark's  Apparatus  for  Softening-  Water — Elevation. 

softened  water  per  hour,  but  there  is  practically  no  limit 
to  the  quantity  which  may  be  supplied  if  the  apparatus 
is  made  large  enough. 

The  lime-water  is  prepared  in  the  small  horizontal 
cylinder  a  by  constantly  churning  up  slaked  lime  with 
water  admitted  under  pressure  direct  from  the  reservoir 
or  main.  By  a  pipe  midway  in  the  height  of  the  churn, 
the  more  or  less  saturated  lime-water  (a  saturated  solu- 
tion contains  about  1*4  g.  of  lime  per  litre  =  0  22  oz.  per 


136 


TEXTILE  FABRICS. 


gal.),  and  with  some  lime  in  suspension,  is  led  into  the 
large  cylindrical  vessel  B,  where  the  lime  and  water  are 
kept  in  slight  agitation  to  assist  in  completing  the  satura- 
tion. As  the  lime-water  ascends,  the  particles  of  lime  in 
suspension  gradually  settle  out,  and  tolerably  clear  lime- 
water  passes  out  at  the  top  into  the  cylinder  c,  where  it  is 
continuously  mixed  with  the  water  to  be  purified  in 
accurately  determined  proportions.  The  supply  of  each 
is  regulated  by  valves  furnished  with  dial  plate  and  index. 
A  brisk  agitation  is  maintained  in  the  mixing  cylinder  c, 
in  order  to  facilitate  the  chemical  reaction  taking  place. 
When  this  is  completed,  the  chalky  water  is  forced  through 
the  filter-press  D,  wherein  the  carbonate  of  lime  acts  as  a 
medium  of  filtration,  and  the  clear  water  thus  obtained 
is  at  once  fit  for  use. 

If  it  be  desired  to  remove  both  permanent  and  tem- 
porary hardness  by  means  of  the  above  apparatus,  car- 
bonate  of  soda,  or  caustic  soda,  must  be  used  in  addition 
to  the  lime. 

Gaillet  and  Huet's  Process  of  Softening  Water. — The 
agents  of  purification  here  adopted  are  lime  and  caustic 
soda,  and  the  cost  does  not  exceed,  say,  one  farthing  per 
1,000  litres  =  220*09  gals,  of  softened  water. 

This  apparatus  differs  essentially  from  all  others  by 
the  simple  but  effective  means  adopted  for  separating  and 
removing  the  precipitated  impurities  without  in  any  way 
choking  the  purifier  or  retarding  the  delivery  of  water. 

Fig.  41  gives  a  perspective  view  of  a  complete  appara- 
tus capable  of  purifying  about  200,000  litres  =  44,000  gals, 
of  water  per  day.  The  purification  takes  place  in  the 
large  square  clarifying,  or  precipitating,  tank  A,  which 
forms  the  body  of  the  apparatus,  and  which  is  shown 
separately  in  Fig.  42,  a  portion  of  the  casing  being  there 
removed  to  show  the  interior  arrangement.  Instead  of 
passing  downwards  through  filtering  screens,  which  would 
soon  become  clogged  and  retard  the  flow,  the  water,  after 
having  been  mixed  with  the  precipitating  reagents,  enters 
at  the  bottom  of  the  tank,  a,  and  rises  slowly  towards  the 
top,  following  a  ziz-zag  course  in  the  shallow  spaces  be- 
tween a  number  of  V-shaped  diaphragms,  inclined  at  an 
angle  of  45°,  and  riveted  alternately  to  opposite  faces 
of  the  tank,  as  also  to  the  two  adjacent  sides.    All  the 


WATER 


137 


diaphragms  shelve  at  the  same  angle  towards  the  same  face 
of  the  tank,  where  they  lead  to  a  series  of  mud  cocks,  F. 

Ahove  the  clarifying  tanks  are  situated  smaller  tanks, 
in  which  the  precipitating  reagents  are  dissolved.  Tank 
b  contains  the  solution  of  caustic  soda,  of  which  the  re- 
quired quantity  is  run  off  into  one  of  the  tanks,  c,  in 
which  lime  has  been  dissolved  in  water.  The  liquid  is 
allowed  the  requisite  length  of  time  to  settle,  the  other 
tank,  c,  being  meanwhile  in  use.  The  clear  soda-lime 
solution  thus  obtained  is  run  off  at  a  regulated  rate,  and 
mixes  with  the  water  to  be  purified  entering  at  D,  in  a 
special  tank  situated  above  the  clarifying  tank,  a,  and 
immediately  below  the  raised  platform.  The  turbid  water 
falls  through  the  pipe  e,  enters  the  clarifying  tank  at  the 
bottom,  and  at  once  assumes  an  upward  motion.  As  the 
section  of  the  tank  A  is  very  large,  and  that  of  the  supply 
pipe  D  very  small,  the  water  naturally  rises  very  slowly 
and  gently,  allowing  the  precipitate  to  settle  almost  as 
if  the  water  were  at  rest.  The  purpose  of  the  Y-shaped 
diaphragms  will  now  be  apparent.  The  water  has  to 
pass  slowly  between  them  in  shallow  layers,  and  as  the 
solid  particles  have  but  a  few  inches  to  fall,  they  readily 
settle  upon  the  diaphragms,  which  represent,  indeed,  a 
very  large  precipitating  area  in  a  limited  space.  As  the 
latter  are  V-shaped,  the  deposit  slides  down  into  the  angle 
towards  the  mud  cocks,  f,  through  which  it  is  discharged 
when  necessary.  The  water  meanwhile  becomes  gradually 
clearer  as  it  rises,  and  is  ultimately  drawn  off  at  the 
top,  G,  perfectly  soft  and  limpid. 

The  process  of  purification  is  carried  on  automatically 
without  the  necessity  of  constant  attendance  or  motive 
power.  It  need  scarcely  be  added  that  the  amount  of 
soda-lime  solution  to  be  mixed  with  the  water  is  deter- 
mined according  to  the  results  of  a  careful  analysis  pre- 
viously made  of  the  water. 

Other  modifications  of  Clark's  process  are  in  vogue, 
differing  chiefly  by  the  mode  of  effecting  the  clarification 
of  the  water  after  mixing  with  the  precipitating  reagents, 
but  the  two  processes  described  may  be  considered  typical 
of  the  rest. 

Purification  of  Water  Discharged  from  Dye-houses. — 
If  it  is  necessary  that  the  dyer  should  have  pure  water 


Fig.  41. — Gaillet  and  Huet's  Apparatus  for  Softening  Water. 


WATER. 


139 


Fig-.  42.— Gaillet  and  Huet's  Precipitating  Tank. 


140 


TEXTILE  FABRICS. 


for  the  successful  prosecution  of  his  business,  he  ought 
to  feel  it  his  duty  not  to  pollute  the  river,  from  which 
he  possibly  receives  his  supply,  with  injurious  discharges, 
to  the  annoyance  and  loss  of  his  less-favoured  neighbours 
lower  down  the  stream. 

Not  only  are  the  waste  liquors  from  dye-works  for  the 
most  part  highly  coloured,  but  they  contain  large  quan- 
tities (over  1*5  g.  per  litre)  of  organic  and  inorganic 
matter,  both  suspended  and  dissolved.  Should  the  dye- 
works  situated  on  the  banks  of  a  small  stream  be  numer- 
ous, the  latter  generally  assumes  a  turbid,  inky  appear- 
ance ;  its  bed  is  gradually  impregnated  with  decomposing 
organic  matter,  putrescent  odours  are  given  off,  the  water 
is  poisoned,  and  the  stream  becomes  practically  a  large 
open  drain,  disagreeable  to  the  sight  and  more  or  less 
noxious  to  health. 

One  of  the  simplest  modes  of  mitigating  this  evil  is 
to  conduct  all  the  refuse  waters  resulting  from  the  various 
operations  of  the  works  into  two  or  more  reservoirs,  where 
they  mix  together  and  precipitate  each  other.  The  whole 
must  be  allowed  ample  time  to  settle,  and  only  the  clear 
water  permitted  to  flow  into  the  river.  Where  space  is 
limited,  filtering  beds  of  coke,  sand,  etc.,  may  take  the 
place  of  settling  reservoirs.  The  purification  is  rendered 
more  complete,  however,  if  additional  precipitating  agents 
are  employed,  such  as  magnesium  and  calcium  chloride, 
lime,  etc.  Of  these  lime  is  perhaps  the  cheapest  and  the 
most  generally  efficacious;  it  neutralises  acids,  precipi- 
tates colouring  matters,  mordants,  soapy  liquids,  albumin- 
ous matter,  etc. 

That  such  a  simple  means  can  accomplish  the  end  in 
view  in  a  most  satisfactory  manner  is  exhibited  in  the 
large  works  of  Mr.  W.  Spindler,  at  Copenick,  near  Berlin, 
in  which  are  carried  on  all  branches  of  dyeing,  printing, 
and  finishing  of  silk,  woollen,  and  cotton  goods. 

In  this  establishment,  according  to  Caspari,  all  the 
refuse  water  flows  into  two  large  collecting  reservoirs, 
where  the  suspended  matter  is  allowed  to  settle.  The 
supernatant  water  is  shown  by  analysis  to  be  strongly 
impregnated  with  salts  of  the  alkalies  and  iron,  together 
with  tannin  and  extractive  matter  from  dyewoods,  fatty 
matter,  colouring  matter,  etc.    After  being  transferred 


WATER. 


141 


to  another  reservoir,  therefore,  it  is  mixed  with  lime- 
water  and  a  solution  of  calcium  chloride;  precipitation 
ensues,  and  the  whole  turbid  mixture  is  pumped  into  still 
larger  reservoirs,  where  it  is  allowed  to  settle.  The  clear 
water  now  obtained  is  found  to  be  simply  a  hard  water 
containing  a  small  amount  of  organic  matter,  and  is 
either  used  for  purposes  of  irrigation  or  allowed  to  drain 
through  the  soil  into  the  river. 

The  solid  matter  which  has  settled  in  the  first  collec- 
ing  reservoirs  is  dried  and  calcined  in  gas  retorts,  and 
yields  per  100  kg.  13-16  cub.  metres  of  illuminating  gas 
(per  1  cwt.,  232-285  cub.  ft.). 

In  bleach-works  the  refuse  liquids  consist  of  alkaline 
and  soapy  solutions,  together  with  such  as  contain  cal- 
cium chloride,  traces  of  bleach-powder,  and  free  acids. 
Here  are  all  the  elements  necessary  to  mutual  purifica- 
tion, if  allowed  to  mix  together  in  due  order  and  propor- 
tion ;  the  calcium  chloride  will  precipitate  the  soapy  solu- 
tions, while  the  free  acids  will  neutralise  and  precipitate 
the  alkaline  liquids  and  decompose  the  waste  solutions 
of  bleaching-powder. 

It  is  impossible  that  any  single  method  of  purifica- 
tion should  be  applicable  to  all  works,  but  the  following 
description  of  a  satisfactory  process,  devised  by  Messrs. 
R.  and  A.  Sanderson  and  Co.,  of  Galashiels,  and  adopted 
by  all  the  woollen  manufacturers  of  that  town,  will  be 
of  interest,  and  may  indicate  what  ought  to  be  done  in 
this  matter  in  woollen  mills. 

The  effluent  water  from  woollen  dye-works  consists 
partly  of  solid  matter  in  suspension — such  as  spent  dye- 
woods,  fragments  of  woollen  fibres,  etc. — and  partly  of 
soluble  substances  contained  in  the  waste  dye,  mordant, 
and  scouring  liquors.  The  method  of  purification  is,  of 
necessity,   therefore,   chemical  as  well  as  mechanical. 

Fig.  43  gives  a  plan  of  the  purification  plant  in  use 
at  Messrs.  Sanderson's  works,  where  upwards  of  40,000 
litres  =  8,800  gals,  of  waste  scouring-liquor  and  about 
120,000  litres  —  26,400  gals,  of  dye  and  acid  magma  water 
are  treated  daily. 

In  order  to  reduce  as  much  as  possible  the  amount  of 
waste  water  to  be  purified,  the  soapy  liquids  from  the 
yarn  and  piece  scouring  are  used  again  in  the  wool- 


142 


TEXTILE  FABRICS. 


scouring.  The  refuse  liquid  from  this  operation  is  run 
through  a  sieve  into  the  settling  tank,  A,  whence  it  over- 
flows at  a  given  point  into  the  large  reservoir  B.  From 
here  it  is  pumped  into  the  high  level  magma  tanks,  c 
(each  of  about  20,000  litres  —  4,400  gals,  capacity),  where 
it  is  thoroughly  well  mixed,  by  means  of  an  air-pump,  p, 
with  a  calculated  quantity  of  sulphuric  acid.  After  being 
allowed  to  settle,  the  supernatant  acid  liquid  is  run  off 
into  the  tank  e  for  further  treatment.  The  precipitated 
magma  of  fatty  matter  is  allowed  to  flow  into  the  pit  d, 
the  bottom  of  which  is  a  drainer  made  up  of  ashes,  spent 
dyewood  chips,  and  sawdust.    Here  it  is  allowed  to  drain 


■Sr. 

N 

M 
i 

G 

a  , 

E 

F  I 

B 

A 

ir 

Road 

C 
C 

c 
c 

D 

K 
K 
K 
K 

mi 
L 

Fig".  43. — Plan  of  Purification  Works  for  Waste  Dye-liquors. 

for  about  a  week,  the  acid  filtrate  being  also  led  into  the 
tank  E.  The  pasty  magma  is  sold  to  oil-extractors  and 
soap-makers. 

The  highly-coloured  discharge  from  the  dye-house  passes 
through  a  sieve  into  the  settling  tank  F,  whence  it  over- 
flows into  the  large  reservoir  G.  In  this  reservoir'  the 
colouring  matter  of  the  spent  dye-liquor,  and  the  unex- 
hausted mordants,  partially  combine  and  precipitate  each 
other.  Tank  H  contains  slaked  lime,  well  mixed  with 
some  dye-house  liquor  from  tank  G. 

By  means  of  the  pump  p  definite  proportions  of  acid 
magma  water,  from  e  (about  one  part),  spent  dye-liquor, 
from  G  (about  three  parts),  and  lime-water  from  H  (about 


WA  TEE. 


143 


one  part),  are  forced  into  the  high-level  purification  tanks, 
K,  and  there  thoroughly  well  mixed.  By  this  means  the 
whole  of  the  colouring  matter  is  thrown  down  as  a  fine, 
flocculent  precipitate.  After  being  allowed  to  settle, 
the  almost  colourless  supernatant  water  flows  into  the 
tank  M,  and  the  deposit  is  run  off  at  intervals  into  the 
pit  L,  and  there  allowed  to  drain  until  it  acquires  such  a 
consistency  that  it  can  be  dug  out  and  conveyed  to  the 
refuse  heap.  The  water  from  the  purification  tanks  K  is 
slightly  alkaline  from  excess  of  lime,  but  in  the  tank  M 
it  is  neutralised  by  allowing  it  to  mix  with  the  slightly 
acid  rinsing-water  coming  from  the  dye-house.  Thus  puri- 
fied, the  water  overflows  into  the  tank  n  and  passes  through 
a  filter  into  the  river  o,  clear,  neutral,  and  free  from 
objectionable  colour. 

The  following  is  an  analysis  of  the  effluent  water  by 
Crum  Brown  : — 


Total  solids  in 
grams  per  litre. 

3 

Colour. 

Ammonia  in 
grams  per  litre. 

Analysis  of  inorganic 
solids  in  grams 
per  litre. 

Organic 
0-13 

Inorganic 
0-78 

1 

3 

Saline 
0-003 

Albumin- 
oid 
0-002 

K0Cr.,07  .    .  0  006 
CaS04     .  .0-11 
CaCOs     .    .  0  32 
Na0S04    .    .  0-29 
NaCl       .    .  0-06 

The  turbidity  is  represented  by  the  quantity  of  china 
clay  (stated  in  g.  per  70  litres),  which,  when  added  to  pure 
water,  gives  a  turbidity  equal  to  that  of  the  sample. 

The  colour  is  represented  by  the  quantity  of  ammonia 
(stated  in  hundredths  of  a  g.  per  70  litres),  which,  when 
added  to  pure  water,  gives,  with  Nessler's  reagent,  a 
colour  as  nearly  as  possible  agreeing  with  that  of  the 
sample.  The  colour  of  the  effluent  water  is  a  faint  brown- 
ish-yellow. 

This  analysis  shows  that,  with  the  exception  of  the 
small  quantity  of  potassium  bichromate,  the  substances 
remaining  in  solution  in  the  water  discharged  into  the 
river,  are  the  usual  substances  found  in  ordinary  spring 
and  river  water. 

In  explanation  of  the  above  process,  it  may  be  stated 


144 


TEXTILE  FABRICS. 


that  part  of  the  lime  used  serves  the  purpose  of  neutral- 
ising the  acid  magma  liquor,  while  the  excess  precipitates, 
from  the  waste  mordant  liquor,  the  hydrated  metallic 
oxides,  which  at  once  combine  with  and  precipitate  any 
colouring  matter  present.  It  will  be  observed  that,  as 
far  as  possible,  the  waste  materials  from  the  various  pro- 
cesses of  manufacture  are  caused  to  aid  in  their  mutual 
purification  and  removal  from  the  water  discharged  into 
the  river. 

In  the  works  of  E.  Schwamborn  at  Aachen,  the  re- 
fuse water  from  the  washing  of  raw  wool,  and  the  milling 
and  washing  of  cloth,  is  precipitated  by  lime.  The  com- 
position of  the  air-dried  precipitate  is  as  follows  : — 

Water    3'11% 

Lime  and  ferric  oxide    ...       ...        ...        ...  18 "47% 

Fatty  matter    7l'96% 

Wool  fibre,  &c   6'46# 

Mixed  with  coal,  this  precipitate  serves  for  the  manufac- 
ture of  illuminating  gas.  Although  in  this  method  the 
potash  salts  of  the  raw  wool  are  lost,  it  is  estimated  that, 
after  deducting  the  working  expenses,  there  is  a  net 
recovery  of  30  %  of  the  value  of  the  soap  used  in  milling. 
In  other  works  the  precipitate  is  treated  for  the  recovery 
of  fat. 


145 


CHAPTER  XI. 

ABOUT  DYEING. 

Materials  and  Colouring  Matters  Used  by  Dyers.— The 
two  most  essential  elements  with  which  the  dyer  has  to 
deal  are  the  material  to  be  dyed  and  the  colouring  matter 
to  be  applied.  With  regard  to  the  former,  our  attention 
is  confined  to  the  textile  fibres,  and  it  has  already  been 
shown  that  great  differences  exist  between  them,  both  as 
to  their  physical  and  their  chemical  properties.  Not 
unnaturally,  therefore,  they  might  be  expected  to  behave 
differently  towards  colouring  matters.  That  such  is  really 
the  case  is  readily  shown  by  making  the  following  simple 
dyeing  experiment. 

Three  pieces  of  clean  white  textile  material — wool, 
silk,  and  cotton — are  immersed  in  a  moderately  strong 
aqueous  solution  of  acid  Indigo  Extract,  and  are  kept  in 
continual  movement  by  stirring,  while  the  liquid  is  gradu- 
ally heated  to  the  boiling  point.  If  the  pieces  are  then 
taken  out  and  well  washed  with  water  they  present  a 
remarkably  different  aspect ;  the  wool  and  silk  have  become 
dyed,  and  appear  pale  or  deep  blue  according  to  the 
amount  of  colouring  matter  employed,  while  the  cotton 
is  not  dyed,  or,  at  most,  becomes  slightly  stained.  If  the 
experiment  is  repeated  with  many  other  colouring  matters 
— such  as  Magenta,  Methyl,  Violet,  etc. — similar  differences 
are  noticed. 

The  real  cause  of  this  striking  difference  in  behaviour 
towards  colouring  matters  exhibited  by  the  different  textile 
fibres  is  still  a  matter  of  discussion.  Several  theories  have 
been  propounded,  but  none  has  gained  general  acceptance. 

It  is  maintained  by  some  that  the  animal  fibres  attract 
certain  colouring  matters  by  reason  of  chemical  affinity, 
and  that  in  the  process  of  dyeing  they  actually  combine 
with  the  soluble  colouring  matter  to  produce  an  insoluble 
coloured  compound.  Cotton,  they  say,  does  not  become 
J 


146 


TEXTILE  FABRICS. 


dyed  because  it  has  no  affinity  for  such  colouring  matters. 
Such  is  the  purely  chemical  theory  of  dyeing. 

The  opponents  of  this  theory  very  properly  urge  as  a 
vital  objection  to  it  that  two  fundamental  signs  of  chemi- 
cal combination  having  taken  place  are  entirely  wanting, 
namely,  the  union  of  the  fibre  and  colouring  matter  accord- 
ing to  chemical  equivalents,  and  the  disappearance  of  the 
special  properties  of  each. 

Experiment  proves  that  the  animal  fibres  may  attract 
either  large  or  small  amounts  of  Indigo  Extract,  and  be 
properly  dyed  in  both  cases,  the  difference  being  simply 
one  of  intensity  of  colour.  There  is  not  the  slightest  ap- 
pearance of  a  combination  according  to  molecular  propor- 
tions, as  in  the  formation  of  Prussian  Blue  by  the  mutual 
reaction  of  ferric  chloride  and  yellow  prussiate  of  potash. 

As  to  the  second  point  of  the  objection,  no  doubt  the 
soluble  Indigo  Extract  attracted  by  the  fibre  has  appa- 
rently become  more  or  less  insoluble  in  water,  but  it  can 
be  readily  removed — by  heating  with  a  dilute  solution  of 
carbonate  of  soda — with  all  its  properties  unchanged,  and 
the  decolorised  fibre  is  also  exactly  the  same  as  before. 

Those  who  adhere  to  the  mechanical  theory  of  dyeing 
explain  the  foregoing  facts,  by  stating  that  the  animal 
fibres  have  become  dyed  by  reason  of  a  purely  physical 
attraction  exerted  between  the  Indigo  Extract  and  the  said 
fibres.  The  latter,  they  say,  are  very  porous  or  absorbent 
bodies,  the  colouring  matter  has  penetrated  the  substance 
of  the  fibre-,  and  is  there  retained  in  an  unchanged  con- 
dition. 

By  this  theory  the  whole  question  is  resolved  into  one 
of  surface  attraction,  and  the  action  is  said  to  be  identical 
with  that  which  takes  place  when  a  weak  solution  of  the 
same  colouring  matter  is  decolorised  by  filtering  through 
animal  charcoal. 

On  the  whole,  the  mechanical  theory  of  dyeing  seems 
to  have  most  points  in  its  favour,  although  it  cannot  be 
denied  that  an  alteration  in  the  chemical  composition  of 
a  fibre  may  materially  alter  its  behaviour  towards  cer- 
tain colouring  matters.  The  most  striking  example  of 
this  kind  is  that  exhibited  by  cotton,  when  changed  into 
oxycellulose  through  the  action  of  hyochlorous  acid. 

Pigments  and  Colouring  Principles  in  Dyeing. — To 


ABOUT  DYEING. 


147 


return  now  to  the  second  of  the  two  essential  elements  dealt 
with  by  the  dyer,  namely  the  colouring  matter ;  so  ex- 
cessively varied  are  the  bodies  belonging  to  this  class,  both 
in  physical  and  chemical  properties,  that  it  is  again  not 
towards  the  same  fibre. 

at  all  surprising  that  they  should  behave  differently,  even 
If  two  pieces  of  wool  are  treated  in  separate  vessels, 
the  one  with  a  solution  of  Magenta  and  the  other  with 
Alizarin,  the  former  will  soon  be  dyed  red,  while  the 
latter  only  assumes  a  brownish-yellow  stain  of  no  practi- 
cal use. 

If  a  third  piece  of  wool  is  first  heated  in  a  solution 
containing  a  suitable  amount  of  aluminium  sulphate  and 
cream  of  tartar,  and,  after  washing  well,  is  then  boiled 
with  Alizarin  and  water  (preferably  somewhat  calcareous), 
it  acquires  a  bright  red  colour. 

When  other  metallic  salts — as  potassium  dichromate, 
stannous  chloride,  ferrous  sulphate,  etc. — are  substituted 
for  the  aluminium  sulphate,  the  wool  becomes  dyed  other 
colours,  namely,  claret-brown,  orange,  purple,  etc. 

If  similar  experiments  are  made  with  magenta,  the 
wool  always  assumes  a  more  or  less  similar  magenta-red 
tint. 

It  is  quite  evident  from  these  experiments  that  Magenta 
and  Alizarin  have  totally  different  dyeing  properties; 
they  are,  indeed,  typical  representatives  of  two  distinct 
classes  of  colouring  matters. 

The  members  of  the  one  class  are  coloured  bodies  or 
pigments  in  which  the  colour  is  fully  developed,  and  they 
require  simply  to  be  fixed  on  to  the  textile  fibre,  more  or 
less,  in  their  unchanged  state,  to  cause  the  latter  to  be- 
come dyed.  Such  colouring  matters  may  be  conveniently 
termed  monogenetic,  since  they  are  only  capable  of  yield- 
ing, at  most,  various  shades  of  one  colour.  To  this  class 
belong  Magenta,  Indigo,  Orcein  (orchil),  Picric  Acid, 
Methyl  Green,  etc.  The  members  of  this  class  may  be 
soluble  (Magenta),  or  insoluble  (Aniline  Black),  organic 
(Indigo),  or  inorganic  (Ultramarine  Blue). 

As  to  the  members  of  the  other  class  of  colouring 
matters,  although  they  are  generally  possessed  of  some 
colour,  this  is  not  an  essential  feature,  and  even  when 
present  it  generally  lacks  intensity,  and  does  not  neces- 


148 


TEXTILE  FABRICS. 


sarily  bear  the  slightest  relationship  to  the  colours  obtain- 
able from  them  in  dyeing.  As  a  rule,  they  are  to  be 
considered  as  colouring  principles  capable  of  yielding 
several  colours,  i.e.  very  distinct  coloured  bodies,  accord- 
ing to  the  means  employed  for  the  production  of  the  latter, 
and  hence  an  appropriate  name  for  them  may  be  poly- 
genetic  colouring  matters.  To  this  class  belong  Hsematein 
(logwood),  Alizarin  (madder),  Gallein,  etc. 

From  what  has  just  been  stated,  it  will  be  understood 
that  the  general  mode  of  applying  the  members  of  these 
two  classes  of  colouring  matters  in  dyeing  is  very  differ- 
ent. This  is,  however,  only  partially  true,  for  the  dis- 
tinction between  monogenetic  and  polygenetic  colouring 
matters  in  this  respect  is  not  sharply  denned,  since  there 
are  those  which  stand,  as  it  were,  on  the  borderland 
between  the  two.  Some  of  the  monogenetic  colouring  mat- 
ters— as  Alizarin  Blue,  Ccerulein,  etc. — combine  the 
properties  of  colouring  principles  and  of  veritable  pig- 
ments. The  method  of  applying  them  to  the  textile  fibres 
is  that  usual  with  the  polygenetic  class,  but  they  are  only 
capable  of  yielding  various  tones  of  one  colour,  and  they 
can  also  be  applied  by  special  methods  adopted  with  cer- 
tain monogenetic  colouring  matters,  for  instance,  Indigo. 

The  presence  of  the  fibre  in  the  third  experiment  cited 
above  is  not  a  condition  essential  to  the  development  of 
the  colour,  as  can  be  readily  enough  shown  by  the  follow- 
ing experiment  :  Make  a  dilute  solution  of  aluminium 
sulphate,  and  render  it  somewhat  basic  and  more  sensitive 
by  neutralising  a  portion  of  its  sulphuric  acid  with 
sodium  carbonate;  add  now  to  the  still  clear  solution  a 
little  Alizarin,  and  shake  the  mixture  vigorously,  or  heat 
it  a  little.  A  red-coloured  body  is  very  soon  produced  in 
the  form  of  an  insoluble  precipitate,  especially  if  a  calcium 
salt  be  also  present.  It  would  appear  in  this  case  that 
the  colouring  matter  enters  into  chemical  combination 
with  the  aluminium,  or  with  a  very  basic  salt  of  the  same. 

Analogous  but  variously-coloured  precipitates  are  pro- 
duced on  substituting  decoctions  of  Cochineal,  Persian 
berries,  Logwood,  etc.,  for  the  Alizarin,  or  by  replacing 
the  aluminium  sulphate  with  solutions  of  other  metallic 
salts.  Coloured  precipitates  produced  in  this  manner  are 
the  real  colours  or  pigments  which  it  is  desired  to  obtain 


ABOUT  DYEING. 


149 


from  the  polygenetic  colouring  matters;  indeed,  when 
dried,  ground,  and  mixed,  say,  with  boiled  oil,  they  are 
used  by  the  painter  under  the  name  of  lakes.  The  object 
of  the  dyer,  however,  is  not  only  to  produce,  but,  at  the 
same  time,  to  fix  these  coloured  precipitates  or  lakes  on 
the  material  to  be  dyed,  without  the  aid  of  such  a  vehicle 
as  boiled  oil. 

To  effect  this,  two  operations  as  a  rule  are  necessary, 
namely,  mordanting  and  dyeing. 

The  Mordanting  Process. — The  first  has  for  its  object 
the  precipitation  and  fixing  upon  the  textile  material 
as  firmly  and  permanently  as  possible,  of  some  substance 
capable  of  combining  with  the  colouring  matter  subse- 
quently to  be  applied,  and  precipitating  it  in  an  insoluble 
state  upon  the  fibre.  This  operation,  or  series  of  opera- 
tions, constitutes  the  mordanting  process,  and  the  metallic 
salts  or  other  substances  used  for  this  purpose  are  termed 
mordants.  This  name  is  derived  from  the  Latin,  mordere, 
to  bite.  It  was  originally  introduced  because  the  early 
French  dyers  considered  that  the  utility  of  these  metallic 
salts  consisted  in  their  corrosive  nature ;  the  general 
opinion  was  that  they  simply  made  the  textile  fibres  rough, 
that  they  opened  their  pores,  and  thus  rendered  them  more 
suitable  for  the  entrance  of  the  colouring  matters.  No 
doubt  some  slight  corrosive  action  does  take  place  here  and 
there,  in  which  case,  of  course,  the  surface  of  the  fibres 
will  be  increased,  entailing,  probably,  a  slight  increase  of 
physical  attraction  of  the  fibre  for  colouring  matters,  but 
the  essential  action  of  mordants  is  undoubtedly  chemical. 
As  to  the  manner  of  applying  these  mordants,  it  varies 
with  the  different  origin  and  state  of  manufacture  of  the 
textile  fibres,  the  nature  of  the  mordants  and  colouring 
matters  employed,  the  particular  effects  to  be  obtained, 
and  so  on. 

The  method  generally  adopted  in  the  case  of  the  woollen 
fibre  is  to  boil  it  with  dilute  solutions  of  the  metallic 
salts,  frequently  with  the  addition  of  acid  salts — such  as 
cream  of  tartar,  etc.  A  partial  dissociation  of  the  metallic 
salts  takes  place,  induced  and  augmented  both  by  the 
dilution  and  heating  of  the  solution  and  the  addition  of 
assistant  acids  and  salts,  and  partly  by  the  presence  of  the 
fibre  itself.    What  actually  becomes  fixed  upon  the  fibre 


150 


TEXTILE  FABRICS. 


during  this  process  is,  in  most  cases,  more  or  less  a  matter 
of  conjecture,  the  chemistry  of  the  process  having  been  as 
yet  only  imperfectly  studied,  although  recent  research 
has  been  turned  in  that  direction. 

Although  the  term  mordant  is  generally  applied  only 
to  the  metallic  salts  used,  a  mordant  in  the  widest  sense  of 
the  term  is  that  body,  whatever  it  may  be,  which  is  fixed 
on  the  fibre  in  combination  with  any  given  colouring 
matter.  In  the  case  cited  of  dyeing  wool  Alizarin  red,  it  is 
considered  that  during  the  boiling  of  the  wool  with  cream 
of  tartar  and  aluminium  sulphate,  this  latter  salt  is  de- 
composed, and  the  mordant  precipitated  on  the  fibre  is 
insoluble  alumina,  or  a  basic  aluminium  sulphate ;  in  the 
subsequent  dye-bath  this  combines  with  the  Alizarin  to 
produce  the  red-coloured  compound,  or  lake. 

Silk  and  wool  have  many  analogous  properties,  and 
hence  the  silk  fibre  is  frequently  mordanted  in  a  manner 
similar  to  that  employed  for  wool,  but  as  a  rule  high 
temperatures  are  avoided,  and  mere  immersion  in  a  cold 
concentrated  metallic  salt  solution,  with  a  subsequent 
washing  with  water,  is  all  that  is  necessary.  During  the 
immersion  the  silk  absorbs  the  metallic  salt  more  or  less 
unchanged,  but  in  the  subsequent  washing  this  absorbed 
salt  is  dissociated  by  the  mere  dilution  with  water,  and 
an  insoluble  basic  salt  is  precipitated  within  the  substance 
of  the  fibre.  Certain  soluble  basic  ferric  sulphates,  basic 
aluminium  sulphates,  and  stannic  chloride,  behave  in  this 
manner. 

As  to  the  methods  employed  for  mordanting  cotton,  they 
are  usually  more  complex,  since  this  fibre  has  not  the  pro- 
perty, like  silk  and  wool,  of  decomposing  metallic  salts  by 
such  a  simple  method  as  boiling  in  their  solutions,  nor 
is  it  so  porous  as  these  fibres.  In  some  cases  metallic  salts 
are  chosen  whose  component  parts  are,  under  certain  con- 
ditions, readily  separable  from  each  other,  such  as  acetates 
of  iron  and  aluminium,  and  with  these,  after  immersing 
the  cotton  in  their  solutions,  and  removing  the  excess,  it 
may  suffice  to  dry  the  cotton  and  then  to  expose  it  for  some 
time  to  air  rendered  suitably  warm  and  moist  ("  ageing/5) 

Ferrous  acetate  absorbs  oxygen  from  the  air  most  ener- 
getically, and  forms  already  in  this  way  a  basic  salt  solu- 
ble with  difficulty. 


ABOUT  DYEING. 


151 


2[Fe(C2H302)2]  +  O  +  H20  =  Fe2(C2H302)4(OH)2 

Ferrous  acetate.  Basic  ferric  acetate. 

In  most  cases  of  mordanting,  however,  whether  the 
material  be  silk,  wool,  or  cotton,  there  is  precipitated  upon 
the  fibre  a  metallic  oxide,  or  a  basic  metallic  salt,  with  a 
corresponding  liberation  of  acid,  or  formation  of  an  acid 
salt,  and  the  mordanting  process  continues  only  as  long 
as  the  constantly  increasing  acid  allows,  i.e.  until  a  state 
of  equilibrium  proper  to  the  new  conditions  has  become 
established. 

The  advantage  of  using  the  metallic  acetates  as  mor- 
dants for  cotton  is  that  the  liberated  acid  does  not  injure 
or  tender  the  fibre,  which  is  readily  the  case  with  other 
salts;  further,  owing  to  its  volatility,  the  acetic  acid  is 
quickly  removed,  under  suitable  conditions  of  heat  and 
moisture,  from  the  field  of  action,  and  a  more  perfect 
precipitation  of  the  real  mordanting  body  on  the  fibre 
takes  place. 

In  some  cases  of  mordanting  cotton  the  use  of  acetates 
and  the  simple  exposure  or  "  ageing  referred  to  are 
avoided,  either  from  motives  of  economy  or  because  cer- 
tain practical  difficulties  arise.  With  cotton  yarn,  for 
example,  the  drying  is  apt  not  to  be  uniform,  and  irregular 
colours  result  from  unequal  decomposition  of  the  acetate. 
Even  where  acetates  are  both  applicable  and  preferable, 
it  is  not  always  the  case  that  the  "  ageing  ,;  process  causes 
the  maximum  amount  of  mordant  to  be  fixed  upon  the 
fibre.  In  such  cases,  other  modes  of  getting  rid  of  the 
acid  are  adopted,  and  other  mordanting  salts  even  are 
employed.  The  mordanting  base  may  be  fixed  upon  the 
fibre  by  using  a  weak  alkaline  bath  of  ammonia,  chalk, 
sodium  carbonate,  etc.,  or  by  using  such  alkaline  salts  as 
not  only  remove  the  acid,  but  also  produce  insoluble  com- 
pounds with  the  base,  as  sodium  silicate,  phosphate,  arsen- 
ate, etc.  This  method  is  adopted  by  the  calico-printer  in 
the  operation  of  "  cleansing  J?  or  "  dunging,"  which  suc- 
ceeds the  "  ageing  "  and  precedes  the  dyeing  operations. 

When  the  mordanting  body  is  applied  in  alkaline  solu- 
tions— as  stannic  oxide,  as  stannate  of  soda — a  slightly 
acid  bath  (sulphuric  acid)  is  required  for  its  precipitation 
upon  the  fibre.  This  is  a  method  also  frequently  used  by 
the  calico-printer. 


152 


TEXTILE  FABRICS. 


Still  another  method  of  fixing  the  mordant  on  textile 
fabrics  is  that  of  steaming,  a  process  adopted  for  certain 
styles  of  work  by  the  printer  of  cotton,  wool,  and  silk 
materials. 

In  the  calico  styles  referred  to,  a  mixture  of  poly- 
genetic  colouring  matter  (as  Alizarin)  and  metallic  salt 
(as  aluminium  acetate)  is  printed  upon  the  fabric,  which 
is  then  dried  and  submitted  to  the  action  of  steam  in  a 
closed  box.  During  this  steaming  process,  the  metallic 
salt  employed  as  mordant  is  decomposed,  a  greater  or 
less  proportion  of  its  acid  is  driven  off,  and  the  remaining 
oxide  or  basic  salt  is  fixed  upon  the  fibre.  Not  only  so, 
however,  but  at  the  high  temperature  employed,  com- 
bination between  the  colouring  matter  and  mordant  takes 
place,  coloured  pigment  is  produced,  and  is  at  the  same 
time  firmly  fixed  upon  the  fibre. 

The  mordanting  and  dyeing  operations  are  combined 
in  an  analogous  manner  when  applying  certain  colouring 
matters  to  wool  by  dyeing,  since  this  fibre  possesses  the 
property  of  decomposing  acid  solutions  of  colour-lakes, 
and  even  of  attracting  and  mechanically  fixing  the  latter 
when  undissolved,  if  sufficiently  finely  divided. 

Colour  Acids  and  Colour  Bases. — In  the  above  cases, 
where  polygenetic  colouring  matters  are  employed,  the 
actual  mordants  fixed  on  the  textile  fibre  have  more  or  less 
a  basic  character;  as  already  stated,  they  are  metallic 
oxides  or  basic  metallic  salts,  and  although  these  colour- 
ing matters  are  not  really  acids,  but  rather  bodies  of  an 
alcoholic  or  phenolic  nature,  they  possess  so  much  of  the 
acid  character  that  they  combine  with  these  and  other 
bases;  it  is  not  at  all  improbable  indeed  that  the  colouring 
matter  and  the  mordant  (when  this  is  necessary)  must 
always  bear  some  such  definite  relationship  towards  each 
other.  All  polygenetic  colouring  matters  known  hitherto 
possess  the  acid  character  referred  to. 

It  has  been  stated  that  cotton  does  not  become  per- 
manently dyed  when  immersed  in  a  hot  solution  of  Indigo 
Extract  or  of  Magenta.  In  so  far  as  this  latter  colouring 
matter  is  a  red-coloured  body,  although  soluble,  it  may  be 
considered  analogous  to  the  Alizarin-red  pigment  pro- 
duced by  the  combination  of  alumina  and  Alizarin.  The 
question  arises,  is  it  similarly  constituted  ?  is  it  produced 


ABOUT  DYEING. 


153 


by  the  combination  of  a  basic  body  with  one  of  an  acid 
character  1  Experiment  answers  yes,  and  shows  it  to  be 
a  chemical  compound  of  a  colourless  base  rosaniline  with 
hydrochloric  acid.  It  does  seem,  therefore,  to  have  a  con- 
stitution somewhat  analogous  to  that  of  Alizarin-red,  but 
of  a  reverse  character.  In  Magenta,  the  colouring  power 
resides  in  the  basic  part  of  the  compound  (rosaniline), 
whereas  in  the  Alizarin-red  it  is  to  be  found  in  the  acid 
portion  (Alizarin),  although  in  each  case  the  other  con- 
stituent is  equally  necessary  to  the  production  of  a 
coloured  body.  Such  considerations  lead  one  to  distin- 
guish colour-acids  and  colour-bases,  and  we  may  infer 
that  if  the  former,  as  we  have  seen,  require  basic  mordants, 
the  latter  will  probably  require  acid  mordants.  Among 
the  numerous  monogenetic  colouring  matters  there  is  an 
extensive  class  of  colour-acids  which  differ  considerably 
in  chemical  constitution  from  those  which  possess  an  alco- 
holic or  phenolic  character  like  Alizarin.  They  contain 
the  atomic  group  (HS03),  are  analogous  more  or  less  to 
acid  sulphites,  and  have  been  termed  "  sulphonic  acids." 
To  this  class  belong  Indigo  Extract,  Crocein  Scarlet,  etc. 
Some  colouring  matters,  as  Indigotin,  may  be  regarded 
as  of  a  neutral  or  indifferent  character. 

In  endeavouring  to  fix  Magenta  upon  cotton,  the  ques- 
tion arises,  will  the  colourless  rosaniline  combine  with  any 
other  acid  than  hydrochloric  acid  to  form  an  insoluble 
red  or  otherwise  coloured  compound  1  Is  it  capable  of 
forming  a  lake  1  If  so,  the  next  question  is,  is  the 
requisite  acid  capable  of  being  fixed  upon  cotton  in  such 
a  manner  that  it  can  still  combine  with  the  rosaniline  1 
Experiment  shows  that  there  are  such  acids,  as  tannic 
acid.  If  a  solution  of  Magenta  is  mixed  with  a  solution 
of  tannic  acid  (either  free  or  neutralised  with  an  alkali), 
an  insoluble  red-coloured  tannate  of  rosaniline  will  be 
precipitated.  Cotton  has  a  natural  attraction  for  tannic 
acid,  so  that  when  once  steeped  in  its  solutions  it  is  not 
readily  removed  by  washing.  In  order  to  dye  cotton, 
therefore,  with  Magenta,  it  suffices  to  immerse  it  for  some 
time  in  a  solution  of  tannic  acid,  and,  after  drying,  to 
pass  it  into  a  solution  of  Magenta.  The  red  tannate  of 
rosaniline  thus  produced  upon  the  fibre  does  not,  however, 
possess  the  character  of  absolute  insolubility,  especially 


154 


TEXTILE  FABRICS. 


in  alkaline  and  soapy  liquids,  so  that  the  dye  cannot  be 
considered  entirely  satisfactory.  But,  just  as  it  has  been 
seen  that  certain  alkali  salts  can  be  used  for  the  better 
fixing  of  the  basic  mordants  on  cotton,  by  reason  of  their 
acid,  so  here  certain  metallic  salts  can  be  used  to  fix  such 
acid  mordants  as  tannic  acid,  but  in  this  case  by  reason  of 
their  base. 

In  applying  Magenta  to  cotton,  for  example,  a  dye 
much  faster  to  boiling  soap  solutions  is  obtained  if  the 
tannic  acid-prepared  cotton  is  passed  into  a  solution  of  an 
antimony  or  tin  salt— such  as  tartar  emetic,  or  stannic 
chloride — previous  to  its  immersion  in  the  solution  of 
Magenta.  By  this  means  the  tannic  acid  is  fixed  upon  the 
cotton  in  a  very  insoluble  form,  as  tannate  of  antimony  or 
tin. 

Acid  mordants,  which  act  in  the  same  manner  as  tannic 
acid,  and  fix  the  basic  colouring  matters  upon  cotton, 
are  not  numerous,  but  oleic  acid  and  other  fatty  acids 
may  be  mentioned  as  such.  It  is  interesting  to  note  that 
colouring  matters  of  an  acid  character  (as  Alizarin)  when 
fixed  on  cotton,  may  also  behave  as  mordants  towards 
basic  colouring  matters.  Alizarin  purples  and  Alizarin 
reds  on  cotton  can  be  readily  dyed  with  Methyl  Violet, 
Magenta,  etc.  Hitherto  all  the  acid  mordants  employed 
to  fix  any  particular  basic  colouring  matter  on  textile 
fabrics  have  produced  only  similar  shades  of  colour. 
Basic  colouring  matters  are  hence  all  monogenetic. 

Since,  however,  both  oleic  and  tannic  acid  can  combine 
not  only  with  organic  colour-bases  in  the  manner  just 
described,  but  also  with  certain  metallic  oxides  (inorganic 
bases),  to  produce  insoluble  compounds,  they  may  be,  and 
are,  indeed,  employed  as  fixing  agents  for  the  latter  in  the 
same  way  as  the  alkaline  phosphates,  arsenates,  etc. 

A  usual  method  of  dyeing  cotton  black,  for  example, 
is  first  to  impregnate  the  cotton  with  a  solution  of  tannic 
acid  (decoction  of  sumach,  etc.),  and  afterwards  with  a 
solution  of  a  ferric  salt  (nitrate  of  iron). 

The  mordant  (ferric  oxide)  is  in  this  way  fixed  on  the 
cotton  by  means  of  the  tannic  acid.  Thus  mordanted, 
the  cotton  is  ready  to  be  dyed  in  a  decoction  of  logwood. 

Another  notable  example  of  the  same  kind  is  afforded 
by  the  method  employed  in  dyeing  Turkey-red.  Here 


ABOUT  DYEING. 


155 


the  cotton  is  first  impregnated  with  oleic  acid,  or  other 
oil  compound  of  a  similar  character,  and  is  afterwards 
immersed  in  a  solution  of  an  aluminium  salt.  The  mor- 
dant alumina  is  fixed  on  the  cotton  by  means  of  the  oil 
compound,  and  yet  it  combines  with  the  Alizarin  in  the 
subsequent  dye-bath  to  produce  the  red  pigment. 

Apart  from  this  preliminary  precipitation  and  fixing 
of  the  basic  or  acid  mordant  on  the  cotton  previous  to 
the  application  of  a  colour-acid  or  colour-base,  the  fixing 
of  all  colouring  matters  upon  cotton  seems  to  depend 
largely  on  their  capability  of  forming  insoluble  precipi- 
tates or  lakes. 

Colouring  matters,  like  Indigo  Extract,  Crocein  Scar- 
let, etc.,  which  do  not  form  any  sufficiently  insoluble  com- 
pound with  bases,  are  not  suitable  for  dyeing  cotton. 

In  dyeing  with  Indigo  and  Safflower,  the  colouring 
matters  are  themselves  readily  precipitated  from  their 
solutions,  either  by  oxidising  or  acid  influences. 

With  Turmeric,  and  some  few  other  dye-stuffs,  pre- 
cipitation is  not  necessary,  since  cotton  is  dyed  with  these 
by  merely  steeping  it  in  their  decoctions,  and  the  case 
seems  to  be  analogous  to  the  dyeing  of  wool  with  Magenta. 


INDEX. 


Acid,  Action  of,  on  Cotton,  14 

 ,  ,   Jute,  27 

 ,  ,    Silk,  66,  67 

 ,  ,    Wool,  38 

 ,  Oxalic  (see  Oxalic  Acid) 

 ■  Mordants,  154 

 ,  Nitric  (see  Nitric) 

 ■  Salts  in  Water,  129 

 ,  Sulphuric  (see  Sulphuric) 

Alkaline  Carbonates  in  Water,  129 

  Solutions,      Scouring  Wool 

with,  98,  99 
Alkalis,  Action  of,  on  Cotton,  16-18 

 .t  1           .Silk,  67,  68 

 ,  ,           Wool,  39 

Ammonia,  Caustic,  17,  18 
Amyloid,  14 

Aqua  Regia  for  Bleaching  Silk, 
121 

Atlas  Silk,  53 

Barium  Binoxide  for  Bleaching 
Tussur  Silk,  123 

Baur  on  Chemical  Retting,  22,  23 

Bleaching  Action  of  Sulphur  Di- 
oxide, 117 

 ■  Calico,  74 

 :  Chemicking,  73,  74 

 ,  Cotton,  12,  71-87 

  by  Electrolysis,  87 

 Flax,  26 

— -  Jute,  27 

— :  Ley  Boil,  72 

 Linen,  89-92 

   ,  Chemistry  of,  91,  92 

 ■   ,  Processes  in,  88 

   ,  Reeling  Machine  for,  89 

 ■   ,  P.ubbing  in,  91 

 Liquid,  117 

 ,   ,  Hydrogen  Peroxide  for, 

118 

■  :  Madder-bleach,  74 

 ,  Mather    and    Piatt  Electro- 

lyser  for,  87 

 ,  Oettel  Electrolyser  for,  87 

 ■  Powder,  18,  83 

 ■  Raw  Cotton,  71 

 ■  Silk,  121,  122 

 ,  Singeing  before,  74-78 

 :  Souring,  73,  74 

 ■  Tussur  Silk,  Motay's  Method 

of,  123 


Bleaching  Warps,  71 

  Wool,  115-118 

 ■  Yarn,  116 

 ■   ,  Sulphur  for,  116 

Bluing  Machine,  74 
Boiling-off  Silk,  119,  120,  121 
Bolley  on  Silk  Composition,  64 
"  Breaking  '»  Flax,  23 
Calcareous  Impurities   in  Water, 

125-128 
Calico,  Bleaching,  74 
Cashmere,  33 

Caustic  Ammonia,   Action  of,  on 

Cotton,  17,  18 

 ■  Soda,  Action  of,  on  Cotton,  16 

    for  Purifying  Water,  134 

Cellulose,  12 

 ,  Analysis  of,  13 

 ,  Hydro,  14 

 ,  Impurities  in,  12 

 ,  Nitro,  15 

 ,  Oxy,  16 

 ,   ,  Witz  on,  18 

Chandelon  on  Wool  Scouring,  102 
Chemical  Retting,  22 
Chemicking,  73,  74,  83 
Chevreul's  Wool  Analysis,  41 
China  Grass,  27,  28 
Chlorine,  Action  of,  on  Cotton,  18 

 ,  ,           Wool,  39,  40 

Clark's  Process  of  Purifying  Water, 

132,  133 

  Scale  of  Water  Hardness,  126 

Cloth  Scouring,  111-113 
Cocoon,  Silk,  50,  51 
Cold-water  Retting,  21 
Collodion,  15 

Colour  Acids  for  Mordanting,  152 

  Bases  for  Mordanting,  152 

Colouring  Matters,  Action  of,  on 

Cotton,  69 

 ,  ,           Silk,  69 

 ,  ,           Wool,  40 

    used  in  Dyeing,  145 

  Principles  in  Dyeing,  147,  148 

Conditioning  Apparatus,  Silk,  60 
Corron's  Machine  for  Shaking  Out 

Silk,  55 
Cotton,  9-19 

 ,  Action  of  Acids  on,  14 

 >  Alkalies  on,  16-18 


INDEX. 


157 


Cotton,  Action  of  Caustic  Ammonia 

on,  17,  18 

 ,        Soda  on,  16 

 ,      Chlorine  on,  18 

 ,      Colouring  Matters 

on,  19 

 ,      Frost  on,  13,  14 

 ,      Hypochlorites  on,  18 

 j      Lime  on,  18 

 1   .    Metallic  Salts  on,  18 

 ,      Mildew  on,  13 

 ,      Nitric  Acid  on,  14, 

15 

 ,  ■     Oxalic  Acid  on,  15 

 ,  Sulphuric  Acid  on, 

14 

 ,  Bleaching,  12,  71-87  (see  also 

Bleaching) 

 ,           Powder  for,  18 

 ,  Bluing  Machine  for,  74 

 ,  Chemical  Composition  of,  12 

 Cloth,  Bleaching,  74 

 ,  Dyeing  Black,  154 

 :  "Extracting,"  14,  19 

  Fibres,  11 

   ,  Dead,  11 

— ,  Fixing  Magenta  on,,  153,  154 

 ,  Impurities  in,  12 

 ,  Mercerised,  16,  17 

 ,  Mercer's  Process  for,  16 

 ,  Mordanting,  19,  150,  151 

 ,  Physical  Structure  of,  11 

  Plant,  9,  10 

   ,  Varieties  of,  10 

 ,  Raw,  Bleaching,  71 

Crabbing  Machine,  Treble,  113 
Cramer's  Formula  for  Fibroin,  65 
Cross  and  Bevan  on  Substance  of 

Jute,  26 

Crum  Brown's  Analysis  of  Purified 

Water,  143 
Dead  Fibres,  11 
Degumming  Silk,  119,  120 
Dew  Retting,  22 
Dextrin,  14 

Disease,  Wool-sorter's,  34 
Duseigneur  on  Silk,  49 
Dye-houses,  Purifying  Water  from, 

137,  140-144 
Dyeing,  145-155 

 .  Colouring  Matters  used  in,  145 

 ,           Principles  in,  147,  148 

 ■  Cotton  Black,  154 

 ,  Materials  for,  145 

 ,  Pigments  used  in,  147,  148 

 ■  with  Turmeric,  155 

Ecru  Silk,  122,  123 
Electrolysers  for  Bleaching,  87 
Electrolysis,  Bleaching  by,  87 
Eria  Silk,  53 

Expander,  Mycock  Five-bar,  85,  86 

"  Extracting,"  19 

Fat,  Wool,  43 

"  Felting  "  of  Wool,  31 

Ferruginous  Impurities  in  Water, 

128,  129 
Fibres,  Cotton,  11 


Fibres,  Dead,  11 

 ,  Flax,  Retting,  20-23 

Fibroin,  63-65 

 ,  Cramer's  Formula  for,  65 

Fischer's  Furnace  for  Yolk-ash,  102 
Flax,  20-26 

 ,  Bleaching,  26 

 ,  "  Breaking,"  23 

 ,  Chemical  Action  on,  25,  26 

 ,    Composition  of,  25 

 Fibres,  "Retting,"  20-23 

 :  "Grassing,"  22 

 :  Hackling,  23,  24 

  Plant,  20 

 ,  Physical  Structure  of,  24,  25 

 ,  Properties  of,  24,  25 

 :  "  Retting,"  20-23 

 :  ,  Chemical,  22 

 :  ,  Chemistry  of,  23 

 :   ,  Cold-water,  21 

 :   ,  Dew,  22 

 ■ :  ,  Stagnant-water,  21,  22 

 :  ,  Warm-water,  22 

 ■:  Rippling,  20 

 :  Scutching,  23 

 :  "Spreading,"  22 

Flax-line,  24 

Fleece  Wool,  36 

Foreign  Wool,  33 

Frost,  Action  of,  on  Cotton,  13,  14 

Gaillet  and  Huet's  Water  Softening 

Process,  136 
German  Wool,  36,  37 
Glossing  Silk,  55 
Glucose,  14 

Gossypium  Arboreum,  10 

 ■  Barbadense,  10 

  Herbaceum,  10 

  Hirsutum,  10 

 Peruvianum,  10 

 ■  Religiosum,  10 

Grass,  China,  27,  28 
"  Grassing  "  Flax,  22 
"  Grey-sour,"  80 
"  Grey-washing,"  78 
Gun-cotton,  15 

 ,  Kuhlmann  on,  15 

Hackling  Flax,  23 

Havres  on  Wool-scouring,  100,  102 

Havrez'  Method  of  Utilising  Yolk, 

45,  46 
Hydro-cellulose,  14 
Hydrochloric  Acid,  Action  of,  on 

Silk,  67 

Hydrogen    Peroxide    for  Liquid 

Bleaching,  118 
Hygroscopicity  of  Wool,  34 
Hypochlorites,  Action  of,  on  Cot- 
ton, 18 

 ,  ,    Wool,  39,  40 

Injector  Kier,  81 

Iron,  Testing  for,  in  Water,  128 

Jute,  26,  27 

 ,  Action  of  Acids  on,  27 

 ,  Bleaching,  27 

 ,  Cross  and  Bevan  on  Substance 

of  26 


158  TEXTILE 


"  Kemps,"  32,  33 
Keratin,  36 
Kier,  Injector,  81 

 ,  Mather  and  Piatt,  79 

 ,  Vacuum,  81 

Kolb's    Experiments    on  Retting 

Flax,  23 
Kuhlmann  on  Gun-cotton,  15 
Ley,  or  Lye-boil,  72,  80,  81 
Lime,  Action  of,  on  Cotton,  18 

 ,  ,           Wool,  39 

 ■  for  Purifying  Water,  132,  133 

Lime-boil,  79 
Lime-sour,  80 
Linen  Bleaching,  89-92 

 ,  Chemistry  of,  91,  92 

   ,  Reeling  Machine  for,  89 

Liquid  Bleaching,  117 

Lustre  of  Wool,  35 

Lustring  Silk,  Machine  for,  58 

 ■  without  Tension,  95 

Lye  Boil,  72,  80,  81 
McNaught's     Wool-scouring  Ma- 
chine, 103,  105 
Madder-bleach,  74 

 ,  Time  required  for,  86 

Magenta,  Fixing,  on  Cotton,  153, 
154 

Magma  Process  of  Wool  Scouring, 
Magnameries,  47  106 
Magnesian   Impurities   in  Water, 
125-128 

Marcker    and    Schulz's  Analyses, 

42,  44 
Market-bleach,  86 
Mather  and  Piatt's  Electrolyser  for 

Bleaching,  87 

 .    Kier,  79 

   ■   ■  Singeing  Machines, 

76-78 

Maumene  and  Rogelet's  Analysis 

of  Yolk-ash,  44 
Mercerised  Cotton,  16,  17 
Mercerising,  93-95 
Mercer's  Process  for  Cotton,  16 
Merino  Wool  Fleece,  33 
Metallic  Salts,  Action  of,  on  Cotton, 

18 

 .   ,  ,    Silk,  68,  69 

 ■   ,   ■   ,    Wool,  40 

Mildew,  Action  of,  on  Cotton,  13 

Mohair,  33 

Mordanting,  149-155 

 ,  Colour  Acids  for,  152 

 ,   •  Bases  for,  152 

  Cotton,  19,  150,  151 

 ■  Textile  Fabrics,  152 

 ■  Woollen  Fibre,  149,  150 

Mordants,  Acid,  154 

Motay's  Method  of  Bleaching  Tus- 
sur  Silk,  123 

Moth,  Silk,  47 

Muga  Silk,  53 

Mulberry  Silk,  54 

Mulder's  Analyses  of  Silk,  63,  64 

Mullings'  Method  of  Wool  Scour- 
ing, 106,  107 


FABRICS. 


Mycock  Five-bar  Expander,  85,  86 
 >  Scutcher,  84 

Nitric  Acid,  Action  of,  on  Cotton, 
14,  15 

 ,  ,           Silk,  66 

 ,   •   ,           Wool,  38 

Nitro-cellulose.  15 
Oettel  Electrolyser  for  Bleaching, 
87 

Organzine,  51,  52 
"  Over-retting,"  22 
Oxalic  Acid,  Action  of,  on  Cotton, 
15 

Oxy-cellulose,  16 

 ,Witz  on,  18 

Parchment,  Vegetable,  14 
Permanganic  Acid,  Action  of,  on 

Silk,  67 
Peroxide  of  Hydrogen,  118 
Perspiration,  Wool,  43-45 
Pigments  used  in  Dyeing,  147,  148 
Plant,  Cotton,  9,  10 
Porter-Clark  Process  of  Softening 

Water,  135,  136 
Powder,  Bleaching,  18,  83 
Pyroxylin,  15 
 ,  Soluble,  15 

Reagents,  Influence  of,  on  Silk,  66 
Red-bleach,  Turkey,  86,  87 
Reeled-silk,  52 
Reeling  Machine,  89 
Retting,  Chemical,  22 

 ,   ,  Baur  on,  22,  23 

 ,  Chemistry  of,  23 

 ,  Cold-water,  21 

 ,  Dew,  22 

 •  Flax,  20-23 

 ,  Kolb's  Experiments  on,  23 

 ,  Stagnant-water,  21,  22 

 ,  Warm-water,  22 

 ,   ,  Schenck  on,  22 

Rhea,  27,  28 
Rippling  Flax,  20 
Rubbing  in  Bleaching  Linen  Cloth, 
91 

Sanderson's     Dye-works,  Water 

Purification  at,  141-143 
Schenck  on  Warm-water  Retting, 

22 

Schwamborn's  Dye-works,  Purifica- 
tion of  Water  at,  144 
Scrooping  of  Silk,  54,  55 
Scouring,  46 

  Agents  for  Wool,  97 

 Bath,  98 

  Cloth  (see  Cloth  Scouring) 

 ■  Loose  Wool,  98-107 

 .  Silk,  119-123 

 ■  Substances,  98 

  Union  Material,  113-115 

  Wool  (see  Wool) 

 ■  Yarn  (see  Yarn) 

Scutcher,  Mycock.  84 
Scutching  Flax,  23 
Sericin,  65,  66 
Shaking  Out  Silk,  55 
Silk,  47-70 


INDEX. 


159 


Silk,  Action  of  Acids  on,  66,  67 
Alkalis  on,  67,  68 
Colouring  Matters 

— —    Hydrochloric  Acid 


on,  67 
69 


on,  67 


Metallic  Salts  on,  68, 

Nitric  Acid  on,  66 
Permanganic  Acid 


Water  on,  66 

 ■   •  Zinc  Chloride  on,  68 

Aqua  Regia  for  Bleaching,  121 
Atlas,  53 

Barium  Binoxide  for  Bleach- 
ing Tussur,  123 
Bleaching,  121,  122 
Boiled-off,  119 
Boiling-off,  120,  121 
Bolley  on  Composition  of,  64 
Chemical  Composition  of,  62, 
63 

  Cocoon,  50,  51 

   ,  Classes  of,  51 

 ,  Conditioning,  61,  62 

 ,           Apparatus  for,  60-62 

 ,  Corron's  Machine  for  Shaking 

out,  55 

 ,  Culture  of,  47 

 ,  Degumming,  119,  120 

 ,  Duseigneur  on,  49 

■  ,  Dyed,  Examination  of,  69,  70 

 ,  Ecru,  122,  123 

 ,  Elasticity  of,  59 

 ,  Eria,  53 

 ,  Glossing,  55 

 ,  Influence  of  Reagents  on,  66 

 ,  Lustring,  58 

■  ,   ■  Machine  for,  58 

 ,  Motay's  Method  of  Bleaching 

Tussur,  123 

 ■  Moth,  Eggs  of,  47 

 ,  Mulberry  Silk,  54 

 ,  Muga,  53 

 ,  Mulder's  Analyses  of  Composi- 
tion of,  63,  64 

 ,  Origin  of,  47 

 ,  Physical  Properties  of,  54,  55 

 ,  Raw,  51,  52 

 ,  Reeled,  52 

  Scouring,  119-123 

 •  Scrooping,  54,  55 

 ,  Sericin,  65,  66 

 ,  Shaking  Out,  55 

 ,  Softening,  121 

 ,  Solvent  for,  69 

 ,  Souple,  121,  122 

 ,  Soupling,  122 

 ,  Specific  Gravity  of,  58 

■  ■  Spinning,  47-50 

 ,  Stoving,  121,  122 

 ,  Stretching,  121 

 ,  Stringing,  55 

.  ,           Machine  for,  57,  58 

 ,  Tenacity  of,  59 

 ,  Tussore,  53 


Silk,  Tussur,  Bleaching,  123 

 ,  Waste,  52,  53 

 ,  Wild,  53,  54 

 ,  Winding,  51,  52 

 ,  Yama-mal-,  53 

Silk-glue,  65 

Silkworms,  Rearing,  47,  48 
Singeing,  74-78 

  Machines,  Mather  and  Piatt's, 

76-78 

 ,  Washing  after,  78 

Sodium    Carbonate    as  Scouring 

Agent,  98 
Soluble  Pyroxylin,  15 
Solvent  for  Silk,  69 
Souple  Silk,  121,  122 
Soupling  Silk,  122 
Souring,  73,  74 

Spindler's  Dye-works,  140,  141 
"  Spreading  "  Flax,  22 
Stagnant-water  Retting,  21,  22 
Steaming  Union  Material,  115 
Stretching  Silk,  121 

  Yarn,  Machine  for,  108 

Stringing  Machine  for  Silk,  57,  58 
— •  Silk,  55 
Steeping,  99-103 
Stoving  Silk,  121,  122 
Sulphur    Dioxide,    Action    of,  on 
Wool,  38,  39 

    as  Bleaching  Agent,  116 

  in  Wool,  37 

Sulphuretted  Hydrogen  in  Water, 
130 

Sulphuric  Acid,  Action  of,  on  Cot- 
ton, 14 

Tanks  for  Wool-steeping,  99-101 
Thread,  Linen,  Bleaching,  88 
Tram,  or  Weft-silk,  51,  52 
Treble  Crabbing  Machine,  113 
Turkey  Red-bleach,  86,  87 
Turmeric,  Dyeing  with,  155 
"  Turn-hanking,"  91 
Tussore  Silk,  53 

 ■   ,  Bleaching.  123 

Union  Material,  Crabbing,  113 

   ,  Scouring,  113-115 

 •   ,  Steaming,  115 

Urine  as  Wool  Scouring  Agent,  97, 
98 

Vacuum  Kier,  81 
Vegetable  Parchment,  14 
Vetillart  on  Flax  Structure,  24,  25 
Volatile    Liquids    used    in  Wool 

Scouring,  106,  107 
Warm-water  Retting,  22 
Warps^  Bleaching,  71 
Washing,  Final,  before  Bleaching, 

83,  84 

  after  Singeing,  78 

  Wool,  103 

Wash-water  Products  of  Raw  Wool, 
45 

Waste  Silk,  52,  53 
Water,  124-144 

 ,  Acid  Salts  in,  129 

 ,  Action  of,  on  Silk,  66 


160 


TEXTILE  FABRICS. 


Water,  Alkaline  Carbonates  in,  129 

 ,  Calcareous  Impurities  in,  125- 

128 

Caustic  Soda  for  Purifying,  134 
Chemical  Purification  of,  132 
Clark's  Process  of  Purifying, 
132,  133 

  Scale  of  Hardness  of,  126 

from    Dye-houses,  Purifying 
137,  140-144 

Effluent,  Crum  Brown's  Analy- 
sis of,  143 

Ferruginous    Impurities  in, 
128,  129 
Hard,  125 

Impurities  in,  125-130 
Iron  in,  128 

Lime  for  Purifying,  132,  133 
Magnesium  Impurities  in,  125- 
128 

Mechanical  Purification  of,  131 
Natural  Impurities  in,  125 
Organic  Impurities  in,  130 
Porter-Clark  Process  of  Soften- 
ing, 135,  136 
Purifying,  130,  131 

  by  Boiling,  131,  132 

  with  Caustic  Soda,  134 

  with  Lime,  132,  133 

 ,  at      Sanderson's  Dye- 
works,  141-143 

Schwamborn's  Dye- 
works,  144 

Spindler's  Dye- 
works,  140,  141 
Soft,  124 

Softening,    by    Gaillet  and 
Huet's  Process,  136,  137 

-,           Porter-Clark  Pro- 
cess, 135,  136 
Sulphuretted  Hydrogen  in,  130 
Weft-silk  or  Tram,  51 
White-sour,  83 
Wild  Silk,  53,  54 
Winding  Silk,  51,  52 
Witz  on  Oxy-cellulose,  18 
Wool,  29-46 

Action  of  Acids  on,  38 

    Alkalis  on,  39 

 Chlorine  on,  39,  40 

Colouring  Matters 


on,  40 


39,  40 


Heat  on,  37,  38 
Hypochlorites 


on, 


38,  39 

-  Bleaching, 


of  Lime  on,  39 
Metallic  Salts  on,  40 
Nitric  Acid  on,  38 
Sulphur  Dioxide  on, 

115-118 


Wool  Bleaching,  Sulphur  Dioxide 

Agent  for,  116 

 ,  Chemical  Composition  of,  36 

 ,  Chevreul's  Analysis  of  Raw, 

41 

 ,  Elasticity  of,  35 

  Fat,  43 

 ,  "  Felting  "  of,  31 

 ,  Fleece,  36 

 ,  Merino,  33 

 ,  Foreign,  33,  34 

 ,  German,  36,  37 

 ,  Hygroscopicity  of,  34 

 :  "  Kemps,"  32,  33 

 ,  Loose,  Scouring,  98-107 

 ,  Lustre  of,  35 

 ,  Marcker  and  Schulz's  Analy- 
sis of  Raw,  42 

 ,  Physical  Structure  of,  30,  31 

 ,  Raw,  Chevreul's  Analysis  of, 

41 

Substances  found  in,  41, 


42 
45 


Wash-water  Products  of, 


.  Yolk  in,  40 

  Scouring,  Chandelon  on,  102 

 ,  Havrez  on,  100,  102 

    Machine,  McNaught's, 

103,  105 

   ,  Magma  Process  of,  106 

 ,  Mullings'  Method  of,  106, 

107 

  with    Volatile  Liquids, 

106,  107 

 ,  Sulphur  in,  37 

 ,  Value  of,  36 

 ,  Varieties  of,  29,  30 

 ,  Washing,  103 

 ,  Yolk  in  Raw,  40 

Woollen  Cloth  Scouring  Machine, 

112,  113 

  Fibre,  Mordanting,  149,  150 

Wool-sorter's  Disease,  34 
Wool-steeping  Tanks,  99-101 
Yama-mai  Silk,  53 
Yarn,"  Bleaching,  116 

 ,   ,  Sulphur  for,  116 

 ,  Linen;  Bleaching,  88,  89 

  Scouring,  107-111 

 Machine,  110,  111 

  Stretching,  108 

    Machine,  108 

Yolk,  Havrez's  Method  of  Utilising, 
45,  46 

  in  Raw  Wool,  40 

Yolk-ash,  Analyses  of,  44 

 ,  Fischer's  Furnace  for  Making, 

102 

Zinc  Chloride,  Action  of,  on  Silk, 


Printed  by  Ca     ll  &  Company,  Limited,  Ludgate  Hill,  London,  E.C. 


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Practical  Draughtsmen's  Work.    With  226  Illustrations. 

Contents. — Drawing  Boards.  Paper  and  Mounting.  Draughtsmen's  Instruments. 
Drawing  Straight  Lines.  Drawing  Circular  Lines.  Elliptical  Curves.  Projection. 
Back  Lining  Drawings.  Scale  Drawings  and  Maps.  Colouring  Drawings.  Making  a 
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Practical  Gasfltting.    With  120  Illustrations. 

Contents. — How  Coal  Gas  is  Made.  Coal  Gas  from  the  Retort  to  the  Gas  Holder. 
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Practical  Staircase  Joinery.    With  215  Illustrations. 

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String  Stair:  Measuring,  Planning,  and  Setting  Out.  Two-flight  Staircase.  Staircase 
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Practical  Graining  and  Marbling.    With  79  Illustrations. 

1  Contents. — Graining:  Introduction,  Tools  and  Mechanical  Aids.  Graining  Grounds 
and  Graining  Colors.  Oak  Graining  in  Oil.  Oak  Graining  in  Spirit  and  Water  Colours. 
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Painters'  Oils,  Colors  and  Varnishes.    With  Numerous  Illustrations. 

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Practical  Plumber's  Work.    With  298  Illustrations. 

Contents. — Materials  and  Tools  Used.  Solder  and  How  to  Make  It.  Sheet  Lead  Work- 
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Practical  Pattern  Making.    With  300  Illustrations. 

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TECHNICAL  INSTRUCTION  {Continued). 


Practical  Handrailing.    With  144  Illustrations. 

Contents. — Principles  of  Handrailing.  Definition  of  Terms.  Geometrical  Drawing. 
Simple  Handrails.  Wreathed  Handrails  on  the  Cylindrical  System.  The  Uses  of  Models. 
Obtaining  Tangents  and  Bevels.  Face  Moulds :  their  Construction  and  Use.  Twisting 
the  Wreath.  Completing  the  Handrail.  Orthogonal  or  Right-angle  System  of  Setting 
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Setting  out  Moulded  Caps.  Intersecting  Handrails  without  Basements.  Index. 
Practical  Brickwork.    With  368  Illustrations. 

Contents. — English  and  Flemish  Bonds.  Garden  and  Boundary  Walls.  Bonds  for 
Square  Angles.  Excavations,  Foundations,  and  Footings.  Junctions  of  Cross  Walls. 
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and  Construction.  Hollow  or  Cavity  Walls.  Chimneys  and  Fireplaces.  Gauged  Work 
and  Arches.  Niches  and  Domes.  Oriel  Windows. 
Practical  Painters'  Work.    With  Numerous  Illustrations. 

Contents. — Objects,  Principles  and  Processes  of  Painting.  Painters'  Tools  and  Appli- 
ances. Materials  used  by  Painters.  Paint  Mixing.  Preparing  Surfaces  for  Painting, 
Painting  Woodwork,  Painting  Ironwork,  Painting  Stucco  or  Plaster;  Distempering 
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